I use a High Sierra Soaker 2-Liter pack on all my rides. It has to pockets large enough to carry my wallet, keys, cellphone, and an extra tube, but there is still additional space. It also has a helmet net. All this for $40. I would have liked to buy a Camelback but I’m a stingy bastard. The only problem I’ve had with it is it leaked where the tube meets the bladder, but teflon tape fixed that problem. There are several others that use the same pack around here.