Sexiest accent?
Certainly not mine. I was brought up to believe that I didn't have an accent - until I changed schools in my mid teens, when I found out pretty sharpish that I DID have an accent, and it was one of the most despised accents in these isles; the strangulated RP.
It's taken years of reverse elocution to iron it out (I blame the parents, meself) but it still sometimes causes problems. As GBS said, an Englishman only has to open his mouth for another Englishman to despise him.
Thus singing can be a problem. How the hell do you sing a song about rural hardship/mining disasters/drowned fishermen when you sound like a bloody BBC newsreader? Putting on a cod accent seems to me to be a cop-out, but I can't think of any other way around the problem.
Strangely enough, the accent is only a handicap in England and Scotland; not in Ireland, the USA or any other anglophone country - in fact it's been quite handy in the US, as I'm often dragged on screen by CNN and CBS to talk bollocks about the Royal family and the British constitution solely on the basis that I can sound like an archetypal chinless twat.
Mind you, its' different when I'm drinking. I don't know if anyone else migrates northward with every pint, but I find that after two or three there's a definite Midlands twang, and after five or six I can be unintelligibly Glaswegian! (...so perhaps I should only sing when pissed?!)