Many programmers do prefer Unity over UE 4 (not UE 3), It’s also for good practical reasons. As an artist I don’t blame them at all. In fact we were able to get actual game done in Unity vs trying to get it done in UE 4 because of it, UE4 is still under construction phase, many things are constantly changing from version to version that could drive developers crazy and some of old timers i spoke to really hate blueprints for their own reasons, plus some things in UE4 can look more time consuming than necessary for a programmer who is used to Unity. As an artist i found the interface of Unity to be straight forward as well. I still prefer UE 4 for those pretty looks, shaders and lighting if you are doing something crazy, but everything else Unity can handle very well. In fact it can handle some things better. I feel UE needs a much larger team to handle it sometimes.
Simplest of examples: when i first started with game engines I had no clue how to view my game with my camera setup, in UE 4 I had to go through a blueprint and then some, and then i forgot again and had to look it up every time to remember how or ask the programmer to help me remember and sometimes it just didn’t work at all. In unity I didn’t even need a tutorial and it just worked. Parent camera to predetermined path plus script if you need it press play and its what you see is what you get, done deal. Some overly simple things like that can make you happy as an artist starting or working in a game engine.
In the end we felt more productive there for medium to small games.
Plus Don’t forget Unity has a strong user base and a very strong market for scripts you can use and tweak to help you out and learn, I think that’s another attractive feature for small teams in case they need them.
Lastly I always felt the Devs behind Unity have a more clear cut direction as to where the engine needs to go (even if its slow to implement sometimes) while I feel that sometimes UE is trying to please everyone with everything at the same time. The latest updates sound great and they hired some industry vets recently to start massively boosting the graphic engine, lighting and shading + performance in Unity I feel UE 4 would have some serious competition then. And that would be great more options for us users : ).