I keep hearing people mention all of these apps, and I've tried most of them (I'm on Android, and besides Sync, I currently have Liftoff, Connect and Thunder installed; I had Jerboa and the Voyager PWA, but removed the former due to bugs and the latter due to slow startup).
Honestly, none of them feel as polished as Sync. They do offer pretty much the same functionality, sometimes even better, but the UI and UX of Sync is just smoother.
Maybe it's just that I'm used to Sync after using it for reddit for many years, but in any case I thought I'd put this out there in case others were feeling puzzled as I was from all the mentions of other apps suggesting they can replace Sync without any quality loss. Sure, maybe not functionality-wise, but to me the user experience is just as important.
Edit: for reference, here's an album of screenshots comparing the same views in Sync, Liftoff, Connect and Thunder (yeah, I'm a fan of the compact list view): https://imgur.com/a/MvawTYm — there are pros and cons to all of these, but IMO the sync experience is the one with the best design and UX polish. Happy to hear your thoughts, though!