I have a couple off brand water bladders. One is an Outdoor Products, the other is a Cabela's branded bladder. My wife has a Camelbak.
The Outdoor Products one I carry more often. It's smaller, so is better for the shorter hikes. I also like it because the hose is easy to remove, as is the bite valve, so it makes it a lot easier to clean and dry out. It doesn't seem as well constructed, but has been holding up just fine. The one thing I don't like about it is that it is hard to get the clip in my backpack through the top of the bladder to hold it upright. It seems to be made to use with the Outdoor Products backpacks with a velcro strap instead of a clip to hold the bladder in place.
The Cabela's one is of better construction of both the Camelback and Outdoor Products, at least a tougher material anyway. It's pretty tough to get the hose off the bag, and valve from the hose. It doesn't use a bit valve either, it's more like the type of valve you find on a water bottle, so you always have to remember to close it after getting a drink. So, not really much of an issue.
I can't comment much on the Camelbak, but my wife really seems to enjoy it. It has a wider opening for filling water, and the hose and valve will come off with a bit of persuasion, so cleaning everything is possible.