Since the game is ever changing you are going to want something than can handle the game and a bit more. I personally like Intel, but AMD is good as well. Go with a Quad core Processor and anywhere from 8gb to 16gb of Ram Memory. If you go Intel, look for either a gt/gtx 650 or better. (Again this all depends on price range). Windows 8 or even win 7 both must be 64bit though.
This one isn't bad:
If your not on a strict budget:
or if you wnat to play around and build one from Ibuypower.com you can go there as well.