I don't see how someone elses personal preference regarding mates is any of my business, but since you want my opinion here it is.
Homosexual? Good for you that you know what you want/like! Just don't expect me to be happy about it if you force it upon everyone you meet. (Seriously, I've seen this so many times it pisses me off. No, you can not recieve preferential treatment because of your sexual preferences! And don't even TRY to go with the "homophobic" excuse if someone doesn't like the fact that you are forcing your sexual preferences on everyone. You don't see heterosexual people going all "oh look at me and how heterosexual I am!" now do you? >_>)
Bisexual? Again, good for you that you know what you want/like! Now, this one is a bit iffy to speak about for me though. I was one of them who believed that those who call themselves bisexual was just after sex constantly and didn't care what gender their mate was as long as they got what they wanted... Then I met a woman who describes herself as a bisexual (she's one of my best friends). I guess what I said about homosexuals fit under here (the "don't force your sexuality upon others"-part).
[Question for bisexuals: How can you have no preference? Or is it that your preference is both genders? I really don't get this, feel free to enlighten me, either by quoting me or PM-ing me].
Heterosexual? Get the hell off my lawn! (Just kidding of course, since I'm a heterosexual myself). I dunno, I don't really got any thoughts worth mentioning on this topic that hasn't been said in the other two. Good for you that you're part of the majority? xD
Also, just a final note. I do not mean to sound offensive or anything. If I offended you in this post, I sincerely apologize.