In reply to carievans67:
I am happy Camelbak Antidote user. Can't really compare with anything else as it is only second hydration bladder (the first one was cheap and water tasted like plastic - used that bladder only once).
Few suggestions:
1. Removable hose might be practical.
2. Wide opening is a must (in my opinion). It just makes cleaning, refilling and other things easier.
3. Valve locking mechanism is useful too. Antidote has it, but once I was descending via South-West side of Carn a'Mhaim and it was quite steep slope, to be honest. I touched the rock with my chest and then I realised that I also "pressed" the valve and it started to leak on my chest. Although it was not THAT risky, I suddenly realised that as soon as water had reached my boots, I would be in trouble.
If you also plan to use it in winter, neoprene sleeve would be useful, too. I noticed that after I refill the pack with chilly water from the streams, the water which is in the hose gets warm in the Summer. I suspect it might freeze in the Winter! In that case, you can actually blow some air through the valve and that way you fill the hose with air. It works, but after a while your hydration bladder will have much air in it. Also, after you refill you can put your bladder upside down and then suck all the air which was left in the bladder. Works well with my Antidote if I don't have much space in the rucksack.
Post edited at 11:01