CamelBak Omega HydroTanium Hydration Reservoir
Five star rating from 103 other reviewers. Not much I can add. If you are hesitant on size, remember you don't always have to fill it full.
Add an insulated hose and an on/off valve and you are good to go. An on/off valve also helps prevent minor spilling when threading the bite valve through the backpack while packing before a hike(noticed my carpet was pretty wet, had the backpack resting on the bite valve opening it up)