which imac should I get if I want to do motion graphics with high performance

I am looking into a new cmputer. I am wondering what I should I prioritize if I am looking for high performance in motiongraphics/colorcorrection/video work. I want to use Apple application as well as Adobe creative suite. I like the sound of a 3.2 Ghz processesor but is that more important than RAM? what about video card? I am trying to understand which component accounts for fast performance most.

Thank you

Johnny