I switched to Fedora after aging out some old Mac hardware only Ubuntu seemed to support. My primary motivator was the appearance of Amazon on my Unity desktop and Canonical's increasing desire to go it's own way with technologies like Mir.

I've been very happy with Fedora and Gnome 3 since the latter hit 3.12 or so. There are still some edge cases like the ability to snap windows to corners that I really think should be addressed but otherwise I'm a happy camper.