Green, straight. I usually have looseleaf, but I've got a little can of the matcha powder that I haven't had much of yet. I like genmai quite a bit.
Ito En sells a lot of bottled, unsweetened teas - green, oolong, and others - in the US that are way tasty. I like their oolong better than any of the bagged oolong I've had - including Twinings' oolong up there - but some of the fancier oolong I've had in cafes is delicious. And the green jasmine blend is to die for. Ito En has some stiffer green brews that are on the Japanese market and that have been sold canned in the US under the Dr. Weil label that are just awesome.
Mugicha (barley tea) is great. I don't know what makes it quite so refreshing, but it just is. I'm not as good at making it as my friend, though.
I have a canister of Russian Kousmischoff tea that is wonderful and slightly citrusy, and it's great with a bit of apricot jam in it.
I'm not a fan of bagged chais. I used to have the chai at Starbucks/Borders a lot, but recently I've tried Third Street Chai's Ginger Spice liquid concentrate, and now everything else is too sweet. I like the strong, spicy stuff, in chai latte form.