I’ve used both Lemmy and Kbin. I see advantages to both, but I have been finding that Kbin isn’t as flexible with federated posts and is less flexible with smaller instances: my smaller instance of Kbin is missing a lot of posts and images that show up on kbin.social.
My smaller instance of Lemmy (VLemmy) seems to be pretty complete, so I have been been happy with it.
Also, the constant Kbin warnings about missing info on Federated magazines has really pushed me toward Lemmy.
My experience with Kbin is that it seems more limited on Federated posts and that the smaller Kbin instance (I use Readit.buzz) seems to be lacking some of the posts and thumbnails that I see on Kbin.social. It seems like Lemmy works better on the smaller instances (not Lemmy.world) than Kbin does (not kbin.social).
I have not really used the Kbin microblog—I am using Mastodon for that.