In reply to LastBoyScout: Lezyne packs were very well designed, helped to be super organised, but now discontinued.
I use a small Hydrapak (soquel)for rides in summer and a larger evoc (FR Trail) pack for winter and longer rides where I want to carry a little more "just in case". The large hydrapaks are very good, but I wanted something a little more bling to go with my Yeti!
Both use the hydrapak bladders which I have found to be the easiest of any bladder I've ever owned to clean. You can turn them inside out rather than buying a stupid "drying rack".
Many pack manufacturers use them in their own packs, Evoc, Da Kine for example.