AMD R9 390 or GTX 970 for Planet Coaster?

[Isolated Fear]

I am considering getting a PC with 6th gen Intel Core i7 6700 CPU (quad core, 3.4-4Ghz, 8MB cache) with 16GB DDR4 RAM.

I actually had my pc built to these specs with a Zotac GTX 970 and I have no issues running the game on max settings. At one time I had a full park with loads of trees and there was a very slight delay or lag if you want to call it that. That could just be an optimization issue.