I agree with Nalgene use for filter attachment and ease of use with a SteriPen. Camelback's nalgene knockoff is okay as well, although I broke of the bite valve thumbrests within hours of purchase and there are more "parts" to keep clean.

I have several different bladders, worn out more than my share,
I like the Cabela bladder's bite valve the best, lots of flow. And the material it is made of tends to keep a better taste longer.

I bought stainless steel bottles and just recently started using them, they tend to make a lot more sloshy noise than I like. But they are light and "un-crushable" in a sense.

So I usually have a big bladder (pun intended here as well)and a couple of nalgenes/camelback bottles, and one or two other bottles, either commercial PET (standard bottled water) or the stainless.

I'm in the desert, so depending on native water availability (many of the trails we use have springs marked)I may carry half of these empty knowing the spring is up trail.