Kbin and Lemmy.ml mostly. The majority of communities I follow and/or interact with are on Lemmy.World, but this is due to the fact that I have a bunch of rather niche interests and other instances lack content about those.
For example, there seem to be only 2 communities about The Owl House: !theowlhouse (which is pretty active) and !theowlhouse which has a single post that is 6 months old and doesn’t even credit the artist, plus an inactive mod. It’s a no-brainer which one I want to follow.
I guess this “lack of content” will change over time, but as of now, the Fediverse still needs to grow a lot to make smaller communities worthwile.