It depends a lot on how strongly you brew your tea, as well as how caffeinated the tea itself is. In general, white tea has the least caffeine and the most EGCG (a potent anti-acne compound), green tea has a little more caffeine and a little less EGCG, and black tea has the most caffeine and not nearly as much EGCG. White tea is really your best bet. I’ve found a quite inexpensive box of white tea containing 100 tea bags (organic) for under $10 at Whole Foods – Prince of Peace brand, I believe. It takes a little getting used to, coming from black tea, but it’s really quite enjoyable. You should be fine with green tea, too, though I’d generally discourage drinking black tea since it can approach coffee-like amounts of caffeine.