Reasons you would like to be the opposite sex or things you want to import into your sex. And don't go all homophobic now, you can just wish for the parts that you like.
I would like to have as much possibilities selecting clothes as women do. It is completely unfair that women have like a thousand different types of clothes to choose from while men usually have to select from very few items. Besides, dresses just seem really practical things to wear. Or in summer, I would like to wear toga without people staring at me, but no! And, one annoying thing... when there is a formal occasion and I pop in with something imaginative, do you think they will be like "wow, that's a good combination", No! They are like "why doesn't he have black suit like the rest of us?" Argh! Unfair!
Hair styles is another one. If I want to be taken seriously, I need to have a short hair. I had like really long hair and it was always a bad thing in any "official" business. I don't see why it has to be... Women have long hair, short hair, locks, whatever they like, like what the hell, why can't I!? How does having a long hair undermine my credibility?