I was initially put off by the UI of Lemmy that I encountered when I first went to the Lemmy site. I was a little confused as to which instance to join. That's when I stumbled upon kbin.social and that's where I landed my new account. Overall I am most comfortable here.
Since joining, I've encountered Lemmy posts that take me to their instances proper, and the formatting looked different, more like here just with a different colored background. Overall, Lemmy instances seem okay, I just like it here better.
Maybe it's the overall familiarity with the instance, calling main topic pages "magazines," the microblogging option, etc. Lemmy's resemblance is a little closer to Reddit, so that might account for why people decided to go there instead of a kbin instance.