I have almost entirely gone to Platypus bottles in my kits. A pair of the liter size give you just the right size for using chemical water treatments and allows you to be drinking one and treating the second.

The larger models, roughly one and two gallons, are good for camp use and where you are using a bulk filter.

IMO these units are much better than most other options for PSK use. They blow away the condoms and breast milk bags.