I think piercings are sexy. Well, most piercings. Gauges can be hot until they get ridiculously big, then they're just disturbing.
I don't have any piercings myself, though I had a pierced ear for a couple of years. I doubt I'll pierce anything else in the future.
I don't know if I have a favorite type of piercing but it's probably a tossup between navel piercings and nipple piercings.
I once had a girlfriend with a navel piercing. It was very hot. But I understand that nipple piercings can add to one's sexual arousal, making nipples more sensitive to touch. That's probably hotter.
I have a character in my new story, "Camping with Christy," who has several piercings. Nipples, lip, tongue. She loves them and knows how to use them, especially her tongue stud. Of all the characters I've created for my erotic writing, I've got the biggest crush on her. Probably because she's based, in part, on a real person that I have a crush on... who happens to have a pierced lip. ;-)