I use a combination of a one quart canteen, a 2 liter generic platypus/camelback, a 1 liter nalgene, and a 1 liter ss bottle. I use the canteen because I have had it for years and it has my canteen cup that I cook with in the cover. I ues the generic platypus/camelback because it makes a fairly good pillow, it can be stored under my jacket in the winter to keep it from freezing, and it's collapsable when empty for easy carry. I like the wide mouth nalgene because I can store food in it and it's easy to clean. and the ss bottle is the best foot warmer I have ever used in the winter. Depending what I am doing some time I use a Bota bottle/wineskin instead of the platypus/camelback.