As a young female with raging pharamones, LOL of course you'd think my first answer would be, Luke. Nah, now that I've watched the show for as many years as I have, I'd hafta say Cooter is at the top, then Luke, Jesse, Bo, Rosco.
Bo always looked terrific in his jeans - even by the fashion of those days his were tight. Maybe he didn't change 'em, but he changed the way he packed 'em - usually to the left, but sometimes to the right and occasionally seems he just didn't know which side to put everything!