I would reccommend the Asus 750JM which is around £ 800, as it has 17.3" screen, a 2gb NVIDIA GTX 860M, an Intel i7-4700 Haswell processor up to 32GB RAM, 1TB HDD, and a extremly nice battery life. But it weighs nearly 4.5kg. On the lower end of your spending spectrum I would reccommend the Asus G550JK as it has roughly the same specs as the JM but is known to have more heating troubles while gaming and has a relativley loud fan compared to the silent and cool JM.