Anecdotally, I joined Mastodon, found it difficult to find people who I personally know that were on different instances, kind of lost interest and thought kbin might be a better solution for both forums and microblogs all in one place, then my Mastodon instance shut down, and then kbin died too. Hence me being on lemmy.world, as default and stable of a server as there is here.
Bluesky felt fun and familiar right off the bat, my only issue was that it was still so small when I joined. Now that there's an influx of new users, many of whom I followed on the bird site, it just feels like Twitter 2, which I suspect is what most people want.
FWIW I have a highly technical job and consider myself pretty tech literate, so I don't think any of the issues I had with Mastodon weren't things I could've figured out or worked around, I just didn't feel incentivized to bother. I suspect they've smoothed out a lot of the federating issues I saw before, but at this point I'm happy enough on Bluesky to stay put.