I found a study a number of days ago that may interest you.
Here's the summary of the findings of the study:
"Therefore, we conclude that green tea has more health benefits than an equal volume of black tea in terms of antioxidant capacity."
To read the rest of the study go here:
Antioxidant Activity of Black Tea vs. Green Tea -- Lee et al. 132 (4): 785 -- Journal of Nutrition