I'm going to address this particular point about UE4 because I see a lot of misinformation thrown around to disparage UE4 over vendor favoritism.
Firstly, do you know why UE4 is popular?
In today's videogames development, how many platforms do you think videogames developers develop for? If publishers are involved, any large budget game you make had better appear on at least 2 platforms: Xbox One and PS4. Windows PC is actually secondary to these 2. So if you are a developer who needs to develop for multiple platforms, do you want an engine that works on all 3 platforms? Of course!
Unreal Engine is a well known engine that works with Xbox One, PS4 and Windows PC. However, that's not all the Unreal Engine supports. Off my head, I remember it is also supported on iOS, Android, Mac OS and Linux. How about that? If we want ports on more platforms, Unreal Engine is a great start point to ensure easier portability between the platforms.
Can Frostbite do all that? I don't know. As far as I can tell, it's only Xbox One, PS4 and Windows PC, I can't tell you more. Frostbite is not available to me or my company.
And finally, to just hammer home a point that has annoyed me for a while. Unreal Engine 4 is supported on PS4 and Xbox One. It is one of the most popular engines and it works fantastic on the PS4 and Xbox One. The PS4 and Xbox One runs AMD GPUs, yes? So what is the excuse for AMD's poor showing? Bottom line is AMD needs to step up. Apologists for AMD are just giving AMD an excuse not to step up.
Yes, I know why it's popular, I know frostbite is locked down. Just talking about technical superiority based on released games in terms of visuals. Sometimes people will trot out UE4 as the be all and end all in terms of being the state of the art engine in the universe as far as real time rendering of game environments is concerned, and I have yet to see a game with better looking environments and visual effects compared to this new battlefield.
As far as which engine is the best that is able to be used by anyone, UE4 might be the best, I don't know if it's a technically superior engine to something like cryengine 5 or just has better support. People say Unity 5 is technically less than UE4, but is perhaps even more forgiving in terms of support and ease of development.
As a consumer, if I had to play a game and got to choose which engine it was developed with, I'd prefer frostbite 3, because not only does it look good, it performs well across more hardware. This is not a fair fight, part of the increased performance likely comes from heavyweight professionals that are hyper experienced when it comes to game optimizations, I don't think bioware has that kind of technical bench when it comes to performance, but dice does, and they get to leverage that experience to make the game run better and look good.
So again, as an end user, and not a developer, I'd rather see game released on frostbite 3. Even though yes, I'm sure it makes a devs life easier to use UE4 to get a good looking game that at least runs on most hardware, passably well if not as well as frostbite 3.