Short hikes - 32oz Nalgene Bottle, coupled with some iodine tablets.
Mountain Hunting, Longer hikes, or hikes with no known water - 100oz hydration pack and a katadyn filter backed up with some iodine tablets.
Sometimes I also carry a GI Canteen, Cup and Stove... sometimes I carry a 2qt GI canteen.... all depends on what I'm doing, where I'm going, how I'm loaded and what the country's like.