Anime should use UE4. It's pretty much flawless.
As has been pointed out on various graphics forums, UE (UE3 in Xrd's case) has little to do with the result, the technological features they use are actually pretty normal (there's something to be said about one of the tools they use, Softimage XSI, but of course that one's being discontinued). Instead it's all about the hard work that was put into making it look like it does. So the actual logical conclusion is "anime should use hard work", and those that do look good indeed!