The Beatles

Maybe because they're British. A lot of people do like British artists. Personally, I prefer how they sing than say some American artists. It's probably their accent that somehow complement the music they're singing. Well, it's just my opinion.

I'm not sure why, but I do know that they had to very excellent musicians - Paul McCartney is one of the best bass guitar players ever and Ringo Starr is a master drummer. They were good at writing songs, too. In my opinion, their recordings always sounded clear and fresh, maybe because they didn't muddy them with too much instrumentation and the entire presentation worked together, not just as accompaniments to the songs.