Keemun is my favourite but very hard to find in looseleaf form. Otherwise Lapsang Souchong in loose leaf form. But both those only at tea time. For breakfast I prefer builders tea and I'm happy with tea bags.

What I don't understand is why tea bags taste so poor in the USA. My local store sells both PG Tips (in the specialty section!) and Taylors of Harrogate: both claim to be imported from the UK but both do not taste right at all.