Somehow, I hate to say it... but I will:
My initial reaction is that I would take the grope by a woman. I would want to see her first, to decide whether I might rather take the radiation of a naked body scan, or just not fly. I might have to explain the object she feels in my pants. If she looked like a dyke or a dog, I would have to take one of the other options.
If you say you want to opt out, and you see a man with his hands out, or an unacceptable woman, can you change your mind without getting even more airport security attention (like a backroom interview or strip search)? Could you look over the security guards and say, "I'll take that one!"
Call me sexist or what you will, but I wouldn't want my wife to be groped by a male security guard even if she was OK with it. I would be OK with her being groped by a woman if she was OK with it and I could watch.