What material is best for a pour over coffee brewer?
Ceramic will - if preheated - prevent some cooling of your water, but plastic filter-holders don't have much heat capacity so you don't lose much with them, either.  Plastic filter-holders and paper filters have the advantage of not costing much so you can have one at home, one at work, one anywhere else you want...

As with most coffee preparation, a good grinder is paramount and getting freshly roasted coffee is also extremely important.