Stepping up from Tinkercad but to what?

FreeCAD all the way.
The commercial CAD packages are all subscription schemes at this point which are designed around the dual purpose of extracting as much money as possible from businesses and nickel-and-diming hobbyists to death. The megacorporations that own them are actively evil and doing business with them should be avoided at all times.
Blender is not a CAD tool. You can bully it into kinda-sorta doing something that resembles CAD work with plugins, but that's not what it's for.
Sketchup is about the same caliber as TinkerCAD and LibraCAD is 2D only.
That leaves FreeCAD.
- Unfortunately FreeCAD is to professional 3D CAD as wet toilet paper is to kevlar. As someone who's spent thousands of hours in solidworks, FreeCAD is physically painful to use. Onshape is the "free" compromise that generally works well.
  
  Yes, but OnShape is only "free." FreeCAD explicitly allows you to retain ownership of your own work, without requiring it to be percolated through someone else's cloud servers.
  I will go back to carving things by hand out of stone before I rely on cloud based design tools.
  
  Have you tried v1. 0 of freecad? It's a completely different beast and I'm yet to find anything it can't do versus fusion 360 (the previous package I used) . We're actually using it professionally at my job now aswell because of its custom user made work benches and scripting tools which no other package allows.
- Solvespace is also an option. https://solvespace.com/index.pl
  Cad Sketcher for blender exists https://www.cadsketcher.com/
  It is based on the solvespace resolver iirc.
- Blender has a decent cam processor add-on. Solve space and openSCAD are other very good parametric CAD programs.

FreeCAD is open source, free, and recently released a big update that made it much better. Fusion is in a enshittification spiral.
- @asbestos @cosmicrookie second the FreeCAD recommend. Started with it as a complete beginner and really enjoy it
  Edit - I started just after the mentioned update
  
  I'll third it, I used Solidworks before, freecad was fairly easy to adapt to before the 1.0 release, workflow is even nicer now, trying to convince my dad to move to freecad over paying for a sw subscription now that he's retired.
- I believe that most, if not all of the ones that i listed, should be free, or at least have a very useful free version. Freecad I have heard a lot of though, and I see a lot of video tutorials on it, so it would be a good option!

Okay so let's strike a couple out of that list:
LibreCAD is a 2D-only DXF editor. I think it's a fork of an old version of QCAD, which is also a 2D-only DXF editor. Not very helpful for 3D printing.
Sketchup is kinda useful for going "what would my room look like if I laid out the furniture like this?" It produces horrible 3D models. When I used to work at the job shop, I could tell the model had been designed in Sketchup because it had holes and reversed normals and other shit that wouldn't print.
Blender. Blender is a 3D sculpting and animation program; Be your own little Pixar, just add talent. It can be used to make models for 3D printing but it isn't very good as an engineering CAD package.
I would also rule out AutoCAD because isn't it like, architectural software? And like, OLD? AutoDesk's engineering CAD was Inventor for the longest time, and they've been working on replacing Inventor with Fusion360. I'm personally done with AutoDesk, they've chafed my taint a few too many times so I wouldn't piss on them if they were on fire.
OnShape is actually cool tech, but it's drawbackware. In the words of Lando Calrissian, this deal's getting worse all the time.
I personally use FreeCAD, it could be better in a lot of ways but it's not commercial. It's made by the kind of people who are very good at programming computers, but they get full body diaper rash from cornhole to corneas if they try to think about software usability. It's why every concept is replicated 2-4 times in various forms of incompatibility. May the dread god Nyalathotep smite thee should thou chooseth to make a Clone instead of a Link. It's also developed in English by mostly non-English speakers. So you go to their forums and ask "If I need to make two mirror images of a part, what is the correct way to model the left one and then mirror it to get the right one" and they can't get past the grammatical puzzle you just spun for them to answer the technical question.
In conclusion, learn to use a pencil.
- This was entertaining. Thank you.

I tried Onshape and now switched to ondsel which is freecad but with a different user interface.
I've had success with it. I find onshape to be a little easier to work with, but I find owning my files more important.
- Seems like they have closed down in 2024?
  https://ondsel.com/blog/goodbye/
  
  My understanding is many of their changes were merged back into Freecad for the 1.0 release.
  
  Didn't follow that, thx for the info! I'll look to use freecad instead.

Freecad is free. It's a huge pain compared to commercial though. It is a bit better with 1.0, but still. Gets slow when the scene / part gets complicated. Solidworks is pricy, but you can get a 1yr free pass for startups, with year 2 and 3 "discounted". Best cad I tried so far, but fuck the pricing. Fusion pissess me off, can't do things I want to do my own way. Sketchup was a toy last time I tried it. Blender is not CAD software.
- As someone who has to interface professionally with solidworks and everyone at my company on the mechanical side uses solidworks, it is also slow as fuck when the part or assembly gets a bit complicated. Just opening it takes a few minutes. If we have to open solidworks and an assembly from scratch during a meeting, that is 10 minutes gone.
  Definitely has 10x as many QoL and productvity features and much better TNP solutions and heuristics built over decades, plus very useful plugins, but speed and stability are not its strong points 😂
  
  Yeah I recently started switching from SolidWorks to Creo in a professional setting, it is amazing how slow and clunky SolidWorks feels in comparison. The downside is that Creo doesn't hold your hand at all so you better know what you are doing.
  Coming from that side, I have a hard time with the free/inexpensive options available for makers, they just don't work nearly as well.
  
  Depends on what stability you are talking about. For freecad, I have to redo the entire part every time I change a dimension and the program doesn't like it. Which is my main gripe with it - parametric cad that doesn't like its parameters changed. It was worse before the naming problem was solved, but is still a huge issue. With solidworks and the same designs, we didn't get as much lag (though it is a huge resource hog), but changing stuff earlier was a breeze and always worked

Solve space and openSCAD are both great options. I have been learning solve space lately and it is great. I couldn't learn freecad, something about the UI and workflow was just too unintuitive for me.
I was burnt by fusion 360. Had some of "my" designs locked in the cloud when they spent 2 weeks and a dozen emails trying to "fix" my educator access. The fix they really wanted was my credit card details. I refuse to use or teach anyone to use that ecosystem now.

Onshape should be at the top of that list. I use it both professionally and personally.
People get freaked out over the free tier data being public, but if you've ever tried searching for something that's public you'd not worry.
- Onshape also has a great series of interactive tutorials that will teach you everything from basics up to advanced.

I've used OpenSCAD, but I program, and it's aimed at someone who wants to write code to generate their objects.

Just mashing together shape primitives and Thingiverse parts in TinkerCAD is entirely underrated. It’s still primarily what I use unless I need particularly curvy corner.
Fusion360 and FreeCAD are the CAD versions of Photoshop and GIMP (if Photoshop had a restricted free tier). They’re both trying to be a legit piece of CAD software, so there’s a bit of a learning curve coming from TinkerCAD. I found it easier to “feel my way around” Fusion360’s UI. FreeCAD has a layer of, “How did Open Source devs decide to be different here?” on top of learning something new.

I’ve tried Shapr3D and it seems pretty good. Not open-source though. I’ve heard blender is a really good option if you want that, but I’ve never tried it as I don’t really do much 3D modelling

Onshape? Its free for most normal 3d printing stuff, and if you get used to it, its pretty similar to the big boy AutoCAD if you need to use that later..

There are two more alternatives, sadly for Windows only.
Solidedge Free for non-commercial makers, relatively easy to learn. But fucking expensive when you want to go commercial.
Solidworks Relatively cheap for makers and students,really expensive for commercial. The maker version has a reduced feature set,but that's not that relevant for most purposes (more towards simulation and things like that) Personally I would prefer it over Solidedge, but that's more of a personal view.
BUT: Both are Windows only(more or less), and of course commercial.
Sadly FreeCAD is not even close to most professional products - while it can be used for a lot of things,these things will take longer, be often more unstable and less "straightforward".Nevertheless for most non-professional uses,it will suffice.
- Thanks for the tips!
  Can you explain examples of what FreeCAD is lacking at, compared to the pro software? I am not sure what I am going into, but would hate to limit myself or waste time/money just by making the wrong choice at this point
  
  There are two sides of issues with FreeCAD: On one side it has usability issues. The comes largely from the "workbench" concept, so often you will be missing a tool unless you change workbenches which in terms leads to another tool missing. Furthermore the UI is not really consistent in how things are named, how things are done,etc. Same goes for the actual step of editing things. So while you eventually "get there", especially as a newcomer, it will take time and a bit of try and error. Parametric solutions are also very clunky and often not as feature rich. (Which is a pain if using it for woodworking) Another thing that is the whole "derivate" thing most professional CAD solutions offer - e.g. build plans, CAM, BOM, simulation,etc. You can do them with FreeCAD, but it takes some plugins and is nearly as good or comfortable as the professional solutions.
  The other side is performance and stability. FreeCAD is a nightmare when it comes to importing thing with a lot facets or large files, is unstable as fuck when working with large assemblies and generally is slower compared to other solutions. (Even the otherwise not very fast Solidworks is faster)
  In the end I would recommend you to try all three of them (and a few others from the list) and then decide if you can be bothered to use FreeCAD or find another solution worth it more. (Personally I would avoid Fusion,btw. due to the fact that it gets more enshitified daily)

If you are looking for something with less of a learning curve jump from Tinker to free cad, I'd suggest Matter control as a nice free intermediate level workspace.

Get on great with fusion 360. No cost, works well on expiry and import to slicer, really can't complain. As It's also an Autodesk product, there may be similarities but I jumped straight in and haven't used Tinker.

I have moved to onshape it is great except for the fact that all your projects are publically available unless you pay. But I still would encourage using open source cad software if it is inutitive for you.

I found fusion360 and blender to be best for me. Fusion made by same company as tinkercad.
I tried freeCAD and had constant errors (like 20 at a time) and couldn't figure out what was going on even tried googling. And that's when I learned that's just how it goes with that program.
I like blender to make sculpted models. Tutorials and figuring things out myself was frustrating but now I have a decent grasp on the basics and I find it much easier to use and keep learning new things all the time with it.
I've only used fusion for a few projects that required it and had to rely a lot on tutorial videos but I was able to do the modeling. I plan to learn more of it in the future but it's pretty decent so far.
I've not used any of the others you have listed.

I can heartily recommend FreeCAD after the 1.0 update. I've gotten quite used to it and have successfully designed complex systems such as a multichannel peristaltic pump for plant watering and planetary gearbox.

Another option is Alibre. It's a one time purchase and fairly reasonably priced but windows only.
I purchased it about 18 months ago after getting tired of being frustrated by solid works makers hate for its customer.
The makers web ui is impossible to navigate, and Why do I have to log back in and decline cookies after every fucking 6gb solid works update?
With Alibre it never expires, I can use it commercially, and it has 99% of the functionality I need including sheet metal.

Fusion 360 is fantastic. It's free for non-commercisl use. I've been using it for years and have zero complaints. It's polished and powerful.
People complaining about it for ideological reasons have a point, but I disagree that it's in some sort of "enshitification spiral". It's exactly as usable as it was 5 years ago. There are very few features locked behind a paywall, and they aren't important to the average maker.
You can even use Fusion to run a CNC router. For free! With all the polish of commercial software.
Everyone I know at my local makerspace uses Fusion. I don't know a single person who uses FreeCAD. A couple people use TinkerCAD. There's a very large community of Fusion users and getting help is easy.
I am 100% in favor of FOSS. Give FreeCAD a try. I used it years ago because it had a plugin to make convolute gears with a couple of clicks. But don't shy away from Fusion just because of all of the haters on here. Give it a try yourself. I think you'll be impressed by what you get for free.
- Fusion seems legit to me and it's free for non commercial use. It seems more intuitive than other cad software though they all have a learning curve