It depends on what I'm doing.
For guests we use a china tea service, probably a hangover from my mother's hosting. With her you had the tea service, (this one: https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcR6QxgGSXJxVH4cIZjzdVOhJyqGYkzOefOgKv_XBG_Jk-xSi-b2mg
) finger cakes on a china plate, finger sandwiches, sugar bowl, silver spoons, all on a tray with a doily.
If I'm making one of my expensive loose leaf teas those also go in china, i kinda figure the china tea cups were designed with tea in mind and therefore you would (theoretically) get a better experience. (Yes, i'm a total tea snob,
For day to day, whichever mug i grab first, some are thick earthenware, some are thinner china, one is cut crystal glass (vintage french, a gift from DH) and most of them have a logo or funny slogan. Lol.
For the Maintenance man it's a thick earthenware one with the local football club's crest on it, because he supports another team and is always teasing me about it.
Bit of a running joke.
I have to admit, I can't drink cheaper tea, not for any snobby reason but "everyday" blends, like tetley or whatever have a nasty oily fish taste to me, and who wants tea that tastes like sardines? I suspect it has something to do with the teabags, although I once read a theory that the high levels of tannins in most british "big name" brands can react oddly with hard water, and the water here is very very hard, causing an off taste.