Might as well get my 2-cents in. I've read several reviews and comparisons, and the one's I've read the Camelbak won. Especially because of the bite valve. This is a quote from a review in MB mag. "No one, (not even the guys at Hydrapak) liked the hard-plastic, push-with-your-tongue bite valve."
I have 3 Camelbak's, and haven't had a problem with any of them. No leaks whatsoever. The new ones even have a shut-off on the bite valve for transporting.