It all comes down to your budget of course. I have a 13" Macbook Pro Retina, 2.9GHz i7, 8GB RAM, 768MB Graphics and 500GB SSD. The screen and speed improvements over my previous standard dual core, 4GB RAM, 500GB HD Macbook Pro are stunning, and I am very happy with the display for my photography.
The SSD's in the Retina MacBooks are very fast and this has made handling 20MB RAW file off my K5 a breeze.
I travel a lot for work, so the Retina MacBook works really well for me processing images whilst I am on the road.
I am very happy with it - but they aren't cheap