Personally I think briefs are VERY unattractive. It's honestly a big turn off for me to know that's the kind of underwear a man wears. White briefs make me think of either young boys, or old men. Colored briefs make me think of stereotypical gay twinks. (It's nothing wrong with that, it's just what they remind me of)
Boxers and boxer briefs are the sexiest to me. That's what I've been wearing since I was 13. It has nothing to do with style (well, it does now), but boxers and boxer briefs are just the most comfortable to me. Briefs are EXTREMELY uncomfortable for me. Too tight.
The first time we had to change clothes for gym was when I was in middle school. Everyone wore either boxers or boxer briefs. There was one kid who wore briefs that get picked on, but it was because he was not only "weird", but a jerk. His underwear choice had nothing to do with it.
I think the shift in underwear is a generational thing. No one wants to wear what there parents wore. One generation started wearing briefs, the next one boxers. My generation mostly wears boxer briefs, the next generation will probably wear trunks or a mixture of some kind, possibly briefs. It'll all come back in style eventually.