I've used several different brands. I'm not 100% certain but I think I'm currently using Now brand. There are some brands that claim to have better bioavailability, but every brand I've tried seems to work pretty well. Over at AM there is a guy on heavy TRT using nothing but DIM to control his E2 and according to his bloods it is working very well. I personally use a combination of Formestane, I3C and Novadex all at low doses. This attacks the problem from every angle.