I really like "Gunpowder" from Peet's Coffee & Tea. I also just had a tasty pot of tea made by steeping one bag of Ashbys Apricot Decaf. with two bags of green tea.
My favorite, however, is the loose tea that my buddy brought back from China for me last year. We don't know what it's called, but it's a green tea of some sort. We don't know if we'll ever be able to find it again to get some more. We've already consumed about three quarters of the small container that my buddy brought back.