The heavy hitter in this category is going to be the Razer Blade. Besides being thinner at 17.9mm and a little smaller (it also has a 14-inch QHD+ panel too) the Blade's killer feature should be its GeForce GTX 970M part. Although I haven't seen that part either, I'm going to guess a 970M-class GPU is going to smoke the 960M in the G501.
The G501 does have an advantage over the Omen and Blade in battery capacity. Asus has jammed a massive 96-watt-hour battery into the chassis. Compare that to the 70-watt-hour in the Blade and the 58-watt-hour job in the Omen.
Finally there's price. With a quad core part, 16GB of RAM and 512GB M.2 PCIe SSD, Asus says it's going to charge you $2,000. That's really not bad. The Blade with 512GB SSD and 16GB of RAM will set you back $2,700. Ouch. The HP Omen comes much closer when spec'ed with 16GB and 512GB M.2 PCIe SSD: It'll push $2,100.
Sign up for CIO Asia eNewsletters.