I'd say.... Desktop.
All my mates that are gamers, use desktop. Mainly that a laptop with the same.power costs a lot.more and your generally sat a desk/table to.play, so no advantage.to a laptop..
The price of a decent gaming laptop like Alienware is loads, where as you can buy a decent gaming keyboard, wireless mouse (most I know use them.larger roller ball mices!) And sound .... We'll all the components for less.
Plus upgrading the video card, sound card, and ram, is cheaper than laptop sized.