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.