I use a 15" MacBookPro Retina display. It's the fully loaded one with 16GB ram and a .75 TB ramDrive which means expensive but it's amazingly fast and the graphics card is compatible with AE-ray tracing. I could not be happier. I figure that I'll use it for about 20 months and then trade up to the next version. If you can afford it I think it's the way to go and the Retina display is amazingly comfortable to work on.
It's amazingly rugged and survived a tremendous bike crash where me and my shoulder pack were thrown off the bike head first at about 20 MPH.