Obviously this will be a biased post becasue I'm asking on lemmy, but I wanted to hear opinions, since I find kbin's interface to be really awkward and all over the place
While I like the UI/UX experience of Kbin, I will still choose Lemmy for the more reddit-like experience that it offers. I find kbin's nomenclature of magazines as being equivalent to sub-reddits awkward. Furthermore, it's trying to be a blend of twitter and reddit. I like the general free/open source approach of one tool for one job rather than trying to do a bunch of different things sub-optimally.
I started off with Kbin, and it was great because it was initially more straightforward with a more sensible UI. But since they didn't release an API quickly enough, apps like Voyager came in, so I've switched to Lemmy.
It also looks like the UI/UX hasn't changed much when I logged into Kbin, so it feels significantly more stagnant. And once Sync for Lemmy hits the Play Store, I'm probably going to stick with it.
If you want to use a 3rd party app on your phone to browse, then Lemmy is the only choice.
I tried Kbin before I tried Lemmy, and I didn't really like the interface of Kbin much. I'm not really sure what else Kbin has going for it other than the interface. With Lemmy there are actually multiple different interfaces you can use. So as someone who likes choice, Lemmy is the one for me.
I also found Kbin's interface fairly awkward and all over the place. Lemmy's Reddit-style interface is more to my preference personally. If you're concerned about missing out on content from Kbin communities as I was when I first migrated, you can easily subscribe to Kbin magazines through the Lemmy Explorer, that way you'll still be able to see stuff from Kbin without having to deal with Kbin's UI.
I like the UI much better (on mobile - I couldn't even tell you what either one looks like on desktop). The lemmy mobile UI is too disjointed for my tastes - it's essentially just a seemingly random assortment of buttons for a seemingly random assortment of functions. I've tried a few lemmy apps, but haven't been impressed, and I can't be arsed to wade through dozens of betas in the hope that one of them might actually appeal to me. Kbin's UI is fine the way it is, so that's that to me.
And I like kbin.social's "All" better than any of the lemmys I use (.world, .ninja and .one). Kbin.social has a pretty broad range of content, but generally without the botfarm instances, which is just what I want. Lemmy world (when it's working) has too much botspam for my tastes, and while I love lemmy.ninja just on principle, it has a relatively sparse and limited "All." Lemmy.one's "All" is pretty good, but the overall feel of the instance is a bit too weedy for my tastes.