i have only used the camelbaks. i don't think it was a conscious choice to not use others, but for me they have always worked, never leaked and replacement parts are always easily available. i do believe they are overpriced, especially the little add-ons that they attempt to sell, though the shut off valve is a very useful idea - though again, i think outrageous at the price.
i use two models, the unbottle 70oz which has a thermo sleeve and a tube sleeve and the 100oz omega. mostly the former in colder conditions - mountaineering, bc snowboarding, etc. ; any time i expect temps to dip below 20o.
i have used the 100oz omega at least 10X at temps slightly >20o and never experienced freezing in any form. the key as someone (sorry, forgot who) mentioned is to blow back all the h20 from the hose into the bladder after EVERY drink. if you are concerned with freezing, try to put the bladder near your back, though i do not and haven't had any issues with the bladder in a hydration devoted sleeve which is on the back of the pack. also, hot or warm h20 in extremely cold temps is always a good idea to ensure you don't have a freeze out.
i will also carry a nalgene with a neoprene cozy as a backup source in case i do have some critical hydration system failure, and usually hike with stove and pot if there are any questions.
for storage, i always clean with a bleach solution and then store in a ziploc bag in the freezer. i will also replace the hose system every 6 mos. or so as you really can't clean the hose and i'd rather be safe than sorry.
good luck on your choice and enjoy.