I think the best water bottles are the aluminum ones (because they won't leak any undesirable chemicals or what not).
I just became an owner of a plastic water bottle (but only because I won it at my gym). It is reasonably good - I am very anal about the cap, because I insist that I need to be able to just to flip it off with one hand in order to drink. I don't like the bottles where you have to completely unscrew the cap - but that's just a personal preference.
I continue looking for a nice aluminum one that would make me happy. One thing that bothers (with aluminum bottles) that there is no see-through window that would allow you to see how water is left in there.
Dearest Schumeany: Yes, those are size 4 jeans hugging my posterior. Thank you for being such motivation!!!