What is the best Thermos Bottle to buy to be used for backpacking?

If I were shopping for a thermos to use backpacking, I'd get a solid stainless steel one. Why? Because of it's construction, including the vacuum bottle inside, which doesn't use the conventional glass vacuum, it's not going to break if you bump things. And the inside is typically Teflon coated for easy cleaning. I like the 0.5-liter models, but, if you want more capacity, then look at the 1-liter models.

I like the ones made by Zojirushi. REI sells the Zojirushi Tuff Slim for $36 and their Dura for $45. You might find them cheaper elsewhere. They also have 3 REI models. Compare the REI thermos bottles.

Here's some related information:

Zojirushi's home page

There are other manufacturers that make solid stainless thermos bottles. That should be the main criteria for backpacking purposes. Happy shopping!