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I really like the half liter Esbit (VF 500ML stainless steel vacuum flask). It always keeps my hot chocolate or coffee piping hot and comes with 2 cups so you can blow your partner's mind when you hand them something hot and delicious. Esbit has all sorts of food and beverage containers of various sizes to choose from.I'm not a huge fan of HydroFlasks because there's not a separate cup to drink from! So when you get a drink you either scald your mouth or end up drinking a lukewarm beverage after the water has cooled down..
I've used a bunch different brand of thermos over the years and have found the Thermos brand work the best for me. I like using the 16oz size for hot beverages and/ or soup. If you want to use for both hot water and soup go with the Thermos Stainless King 16 Ounce Food Jar with Folding Spoon, Stainless Steel.To use for just hot beverages, check out the Thermos Stainless King 16 Ounce Compact Bottle, Stainless Steel.
Depending on how long I'm going to be out and how cold it is, I actually like using just the Nalgene Insulated 32oz Printed Water Bottle Sleeve. It helps keep water reasonably warm and is a good lightweight option to use when compared to the volume of liquid a 32oz Nalgene bottle holds.
What's the best way to keep liquids from freezing in cold weather?