I've had the Phottix one for nearly a year and a half . I've shot about 70.000 times (press photographer) with it.
I've paid it approximately 75$ (when the Canon could be found circa200$ at this time). And well...it's cheaper, really cheaper than the genuine Canon and...you know it when you hold it in your hands.
70.000 shots after, all the writings (AF-ON ; * ; AF selector) have disappeared and the "leatherette" grinds all around the corners. It starts to come off the grip where i usually put my index finger.
But the worse is that the trigger dies a bit more avery day. It's becoming harder and harder to work with the grip cause i have to press it real strong to shoot.
Well. Just my 2 cents.
It really depends on what you're gonna do with your camera. If you don't shoot a lot, mainly your family and landscapes, it's gonna be fine for shure. But if you use it ardently, with a quite violent background, get the Canon one.