Are there general recommendations for mugs? Is there a general consensus on what some of the best mugs out there are in terms of keeping (drip/pour-over) coffee warm, style, and flavor? Ceramic? Double-walled glass?
Ceramic is more porous than glass, so a ceramic mug insulates better than regular glass and thus keep the coffee hotter, but double-walled glass insulates even better than ceramic.

A porous mug might exchange molecules from one cup to the next. (Is there experimental data on that?)