Lemmy

The user counts for native kbin are much smaller even than the small Lemmy user counts. So a lot of the users you'll be interacting with on kbin will still be Lemmy users in forums homed on Lemmy servers. You'll also have the ongoing possibility of interoperability bugs and terminology confusion around things like "communities" (the Lemmy term) vs "magazines" (the kbin term) and other places terminology varies. I was pondering kbin, but decided that it was simpler to sign up to the app where the people were... the cognitive overhead of having to wonder if I'm seeing content differently than most of the users I'm talking with didn't seem worth it to me.

That said, if you want to interact with both Lemmy in redditlike ways and mastodon in twitter-like ways, kbin does seem to try to be a one-stop shop. I'm only on Lemmy for now, but my plan is to make a separate mastodon account if I end up wanting to... for much the same reasons. So much of how the fediverse "feels" depends on the app you're using, and if I want to do the tootiverse, I'm going to want to experience it through Mastodon directly so I understand how most other people see it.

That said, the fediverse exists to allow this kind of interop. If kbin is doing it for you, enjoy it.