60 FPS average is easily achievable with the GTX 1060 3GB/6GB and RX 470 & 480.
Total War: Warhammer is a very demanding game at 1440P. Only the NVIDIA Cards can achieve 60 FPS with 2560 x 1440 in this game. They are the GTX 1070, GTX 1080, GTX 1080Ti.
The only video card i would recommend playing this game at 4K would be GTX 1080Ti 11GB. It's the only video card that can handle Total War: Warhammer at 60 FPS average.
More coming soon.. for now this is under construction and not yet finished.