Let's run down the options shall we (I'm straight by the way):
Homosexual: This could work out in my favour as I've had quite a few gay men hit on me in the past and hardly any women. I also tend to get along better with women and gay men than with straight men. In my experience gay (and bi) people are often more open minded, both generally and sexually than people that are straight (maybe because they had to fight to be who they are).
Then again I know how hard having a "different" sexuality can be in this society, and I have enough problems as it is so I think I'll pass.
Bisexual: Pretty much the same as above but more complicated. What I mean is that in a relationship men and women both have different things to offer both good and bad. If I were to be attracted to both sexes I fear that when in a relationship with that one special person would still leave me longing for the other sex in one way or the other. So this one is out too.
Asexual: Now where talking. This would free up a LOT of time (and money) to spend productively. It would also eliminate all of the stupid things that our hormones make us do (stupid hormones!). But then I remember why we go through all this trouble and think it's still worth it. Damn you women for being so beautiful! This one is out too.
Let's see, that leaves me with;
Heterosexual: I already know what this entails. Though even heterosexuality sometimes seems more trouble than it's worth I still wouldn't change it. Plus, we already seem to have it the easiest in this world anyway (which isn't fair I know).