You would have to be seen in person to determine what is best for you. I will say that with such large breasts (presumably based upon you cup size) you can not expect to go down to a "C"
This question cannot be answered in the abstract. Information would be desirable as to your height, weight and other factors. The goal in reduction is to alleviate musculoskeletal complaints. Typically, my patients with comparable bra sizing go down to D or large C cups.