CPU. Unless you do a lot of 3D graphics or heavy video the integrated graphics in the new i7s is actually sufficient for most PS work. When I looked into a little over a year ago, the benchmarks I read showed that discrete GPUs didn't really do much over integrated i7 GPU, unless you had a really nice GPU (the $500+ kind). Even then the difference wasn't staggering, to me anyway. One caveat, I did my research back when CC was first released. I know they intend on releasing more GPU accelerated functions, so that could change.
Regardless, any type of use you use Photoshop for will require as much CPU power as you can spare. You can always go back and add in a discrete GPU later if you find performance lacking or Adobe makes significant GPU performance increases you want to harness. Upgrading a CPU can be a lot more costly. Get a solid CPU... highly recommend whatever the latest i7 is. I have the 4770k, but I'm sure that's old news by now.
It's not a fair comparison, but I previously used a Sony VAIO with i5, and then built a desktop with i7... and it is AWESOME. Using my laptop makes me cry now.