You'll want the best GPU, Core i7 and 1080p screen.
If you go for brands, then Dell XPS or Vaio F-series. Alienware is just overpriced gimmick. Otherwise, Asus G53 looks decent. Do some research, post your links here and we'll let you know.
Laptop advice guide: http://www.youtube.com/watch?v=7qE5IQ9tyAE