Yep, got to agree with the Contigo Byron. It's the only one i've had (and i've had many) that is easy to use, doesn't leak and keeps drink hot for ages and for only £12! Best themal mug ive had!!Contigo Byron. 450ml stainless steel but secure top and work well. About £12.
My take on this that is the recommendation is for what are sold as travel mugs. A container to hold liquid in a warm state for an extended period of time while travelling or during work time without spilling. Some have sliding openings to drink from and therefore cannot be put in a bag and taken off to work etc. The Contigo has a pop top that forms a decent seal so won’t spill liquid. It keeps the drink hot during the travel even for long periods, and where it should be, in the mug. Only leak I had from the Contigo was from not preheating the mug properly with boiling water and quickly chucking it in my work bag. Heat expansion squeezed a small amount out.Personally, I would not consider double wall, tall, handle-less, screw top designs such as the Contigo to be travel mugs since they don't do any of the things I want a mug to do when I am travelling...but that is clearly what they are sold as and what some people buy them for, so everyone is different.
Plus one for the forge. Go for the stainless inside though. I’ve been using mine for 3-4 yearsHave a look at the camalbak forge mugs. Had one for ages (and just bought another from go outdoors as they are very cheep now). Robust, spill proof, have a means to attach to a belt, and keeps my coffee very hot for over 4 hrs (in theory that is, it never actually lasts that long).