Submitted by Everett Mobley
Camelbak packs are high quality, but I hate their hydration bladder. It collapses flat and is difficult to clean and dry.
The Platypus bladders expand like an envelope, and they can be free-standing. They are easy to fill and to drain and dry. They have screw-on caps for use as water-bottles if you're not using the sipper tube.
ED -- Everett, which Platypus system do you use? In looking over the selection, it seems that the best bladder to use would be the Big Zip SL, with its slid lock closure system located at the top of the bladder, which makes for easy filling. The other bladder system, the Hoser, has a screw cap, and while the loop at the top makes a convenient hanging point for the bag, the small cap opening would appear to be a drawback (most modern Camelbak bladders have a large diameter opening which allows for you to add ice or what ever easily.) Also, at 2L. (70 Oz.) the Big Zip is still 1L. shy of the biggest Camelbak bladders.