What i've noticed is that each one is lacking something. I kind of like the layout of lemmy a bit more, but it doesn't have the same capability of following people or communities from all over, and I don't think you can follow users at all like in kbin and Mastodon. But kbin doesn't have any way that I can find to save posts, which is something use a lot.
Reddit exodus - Using Lemmy from my existing Mastodon (vijayprema.com)
Many are turning to Lemmy as a viable Reddit alternative. Here is how to use your existing Mastodon account with Lemmy.