Best laptop for 3D modeling / rendering?

(1) discover if your 3D modelling software has GPU acceleration (opencl, cuda, openAcc, etc). If so see what graphics cards accelerate best and buy a laptop with that card.
(2) discover if your 3D modelling software is good a running multi-threaded. If so get at least a quad core.
(3) decide how often you will be running on battery and how often you will be running off the brick. I've seen people at work trying to carry around laptops with 170W bricks that must weigh pounds. I get 4-6 hours w/o recharging. Then choose between efficiency and performance.

" is the nVidia GTX 680M the best... " notebookcheck does a great job of benchmarking. As you can see from the graph here: http://www.notebookcheck.net/NVIDIA-GeForce-GTX-680M.72... that there are video solutions stronger than a 680M.

IF your software uses double precision check a few benchmarks. You might want a Quadro or FireGL. I think I remember the DP float being kneecapped on the 680m.