Personally I started with kbin and think the dev of it is great. But it’s simply not as far along IMO. At least when I was using it, it was critically missing the ability to collapse comments. That single feature is huuuuge for me and probably the most prominent thing that got me to switch to Lemmy.

It also doesn’t have an API yet, which means that mobile apps aren’t likely to target it. Though I’ve personally been using a browser cause I haven’t found any apps to be good enough yet.

Also, the notifications of kbin felt very buggy to me. I missed a lot of notifications and even when they worked, they don’t show the notification or even what the thread title is, so you have to click each one individually. IIRC, clicking the notification also didn’t work if your comment wasn’t on the first page of comments.