I use both. They're similar for simple use, but above a certain level of complexity Hy has a lot of Python-isms that bleed through. It really doesn't ever let you forget that underneath all the parentheses you're really writing Python. Janet feels like its own stand-alone language in that respect, where Hy is more like a syntax swap.

I have the impression that Hy's user base is larger, though (not that either one is huge).