IMac and After Effects CC2017

I'm looking to buy a new computer for professional work with After Effects. I'm leaning towards buying the fastest iMac. Any recommendations on what specifications I need to ad in to the base model? Any problems with working with AE on the iMac: Does it overheat with extensive AE work? Does the graphics card that comes in the iMac support GPU-accelerated effects in AE CC2017?



thanks!