I still prefer win 7, but it is difficult to find a new laptop without win 8.
Given that, I would go for a good Dell E6430 (if you want a good weight/performance tradeoff) or Precision M4800 (if you want a lot of raw power).
If you want some very light stuff, go for a Lenovo X1 Carbon.
If you want light and powerful, there is the Dell Precision M3800 with QHD+ display (that is, however, very expensive)