Bottles: Insulated.

Cost aside—and the cost isn't that much more—there's no compelling reason to buy a non-insulated water bottle. You see, once you have an insulated bottle, the entire spectrum of beverages is open to you: from ice cold iced tea to piping hot coffee. And if you can commit to a "one bottle" lifestyle, you'll always be ready... never caught flat footed... because you'll always have a suitable vessel on hand to hold your beverage of choice. I don't think I need to even mention that we are talking about wide-mouth bottles only: narrow necked bottles just aren't as versatile.Some will say that stainless steel doesn't taste as good as glass or polycarbonate. That's true, but I think the durability outweighs the cost.Also, some will say you can't get the (e.g. coffee) stink out of stainless. That's not true: just soak it for a while in barkeepers friend or baking soda and it will be fresh as a daisy. (Store some mint tea in it for a day and it will be even fresher!)I've tried a lot of them, and I believe that Klean Kanteen makes the best insulated bottles.*  I have had the same one travel with me to four continents over several years, and it has held up with aplomb. I put it in the dishwasher too, and it still doesn't leak.Also: thermoses? Banish that vocabulary. An insulated bottle IS a thermos, but without all the baggage and bad attitude.  You want clean, simple, absolutely reliably leakproof, and easy easy easy easy to clean. * They unfortunately do not make a good "large" bottle, so if you want a 40oz bottle, you have to go Hydroflask, even though they are inferior. Kleen Kanteen does make a growler sized insulated bottle, for which I am grateful.