Like Carrie Ann, I'm voting even though I'm not a guy because, hey, I love breasts too.
And! Before I go any further I want to say that I love ALL BOOBIES because I genuinely think all boobs are amazing! Lop-sided, big nipples, little nipples, saggy, perky, whatever, your boobs are beautiful, people! Love them and never let anyone make you feel insecure about them for any reason because they, just like the rest of your body including your brain and heart, are awesome!
With that said, I will say that my favorite would HAVE to be A although again, all breasts are wonderful. I just really am incredibly turned on by small breasts, like, insanely so. Don't ask me why, but I am.