It's difficult to say. ASUS, MSI, and Lenovo generally have very similarly-priced laptops with similar specs at lower price ranges, but they diverge at higher ones. Gigabyte is a new player in the gaming laptop field and have the best-priced gaming laptop right now, a $1300 powerhouse with a Broadwell i7 and a GTX 970M, but they are not exactly proven in terms of build quality (though they are among market leaders in the motherboard and GPU board industries).
The best answer is that it depends on the price range, as each company has something unique to offer.