My criteria for a water bottle is that it should be leak resistant and reasonably light weight. I prefer wide mouth containers. Thus my all time favorite is the recycled beverage (usually Gatorade) bottle. Slaking my thirst and saving the planet by recycling - such a deal! I have plenty of one liter Nalgenes that I have acquired over the years, and I could care less about their chemical composition. This concern diminishes even more dramatically the more thirsty I get. I do like the tethered cap - a very fine feature.

As the saying goes, the best water container is the one that you have with you, especially if it still contains water or a reasonable facsimile.