I am hard pressed to choose, but if I had to pick a favorite tea, it would be Oolong. It doesn't have the grassiness of many green teas or the astringent bitterness of many black teas. You can over brew it and it still comes out great. It is partially fermented, but not to the extent of blacks, from mostly green to very dark. It can be roasted or unroasted. All this give it an unparalleled range flavors. Try all the whole leaf varieties that you can to discover which are your favorites.