Just to drop a little love for UE4 in here:
5 years in Unity3D, published over 40 “games” (they run, there’s a game loop, whaddya want 
) just jumped into UE4 the day it went free. I’d been sort of champing at the bit to get into UE4, since it seemed to be the only engine with a proper 1:1 physically-based rendering pipeline with my weapons of choice, 3DS & Substance.
Going from zero to production-ready by following everything in the Learn tab of the launcher, then associated docs, has been a real treat compared to when I 1st started out with Unity. Sure, Unity docs have improved a ton since the early days, but any long-time Unity user will remember the bad old days when their docs only had Javascript examples (which was hell because I favored C#).
I can’t really speak to Unity 5, though I did grab a copy when they went “free” too and tried to import my models & Substances… still didn’t look anywhere near as good as UE4 does out of the box. Maybe Unity will get better in time, or with extra plug ins.
I also loved Unity for fast iteration, being able to get prototypes up & running in very short times. Though it will certainly take a few months of dedicated practice, I can already feel that UE4’s Blueprints/Content management plus vibrant community will equal if not exceed the development speed I once enjoyed.
Again, not to lay out a blanket “X is better than Y”, but from my experience thus far I can’t see myself returning to Unity any time soon.
YMMV