Ok well if we aren't just talking bog standard tea such as tetleys or twinings then here's what I like:

Peppermint Tea, so good with a couple of sugars in! Great for settling an upset stomach or for drinking when having a shisha pipe or sweet baklawa pastries.

Earl Grey, a refined taste for some it's very flowery it's not too sweet though if you add sugar it can become almost sickeningly so. This is best drunk black with maybe a dash of cold water to help make it drinkable sooner.

Chamomile Tea, this is something I touch very rarely because 1) I'm not over-keen on the taste and 2) I don't think it works. But it's supposed to help you sleep.

If we're talking stuff like the powdered teas you get from Whittards of Chelsea then well it's always dreamtime tea for me This stuff is L-U-S-H seriously it's great.