The type of cup that keeps water hot the longest is a Styrofoam cup.
Another type of cup that keeps water hot the longest is a stainless steel vacuum insulated cup.
I did this experiment today and found that between my other cups such as the ceramic cup, plastic cup and the regular insulated cups and the Styrofoam Cups and the stainless steel vacuum insulated cup that my vacuum insulated cup and the Styrofoam cup kept the water hot the longest.
The Styrofoam cup with the lid keeps the water hot for a long time.
Insulated coffee mugs with lids also keep water or liquids such as coffee, hot chocolate, hot tea etc hot for a long time.
Or a good insulated thermos is a good thing to have to keep your liquids hot such as hot coffee.
Ceramic coffee mugs are the most common and affordable coffee mug.
The best ceramic coffee mugs keep water and other liquids hotter for longer, without imparting any aftertaste or picking up stains from the beverage.
Ceramic material is more fragile than glass and plastic, it must be used and washed gently.