The best would be loose leaf green tea, and the fresher the better. Green tea begins to lose its good properties after about 6 months. The green tea at the supermarket has been in a warehouse for who knows how long. Also, the green tea in teabags is usually much finer and is usually poorer quality. I don't know anything about bottled green tea because I've never tried it. I don't think it would be as good for you, though, since it's not freshly brewed.
So I would guess that loose leaf is best, bagged is second, and bottled is last. That's just a guess
I buy loose leaf green tea from
www.adagio.com and love it.