What's the best material for a camping mug?

It depends on how you camp. Titanium cups (like the TOAKS and Snow Peak models here) are favored by backpackers for being extremely light and stove-safe, but single-wall metal transfers heat to your lips and hands. Double-wall insulated stainless steel (YETI, SUNWILL, Volhoply) keeps drinks hot longer and stays cooler to hold, but is heavier and usually can't go over a flame. Verified-purchase volume in this pool skews toward both titanium and insulated stainless.