I have to pick just one?
I don't even know where to begin, really. I saw/see no upside to it. When I was little, it seemed every adult I was introduced to immediately started talking to me about football (the American variety, with the big dumb manly men tackling each other), just because I was a boy. I
loathe sports. Probably in large part due to this early experience. I got so sick of people forcing it on me all the time. Luckily, it only took a few failed attempts for my dad to realize there was no hope of ever getting me to actually play any.
Like Stephanie C said, I hated how other men acted. The dumb macho posturing. The insensitivity. The way they were so emotionally unavailable. The degrading and dehumanizing way they talked about people, especially women.
And I'm still trying to figure out what in the world people mean when they say I had something called "male privilege."
And those are just the social things. As for physiology, males get to enjoy such lovely features as hair covering their bodies (yuck!), hair falling out on your head, rougher skin, dangly genitals that constantly have to be adjusted to stay comfortable and just look unsightly, deep voices...
Yeah, there's nothing at all I like about this gender, from either an anatomical or social standpoint.