Merlin is less conventionally pretty/handsome/beautiful/pick your word than Arthur, imho. Which works out well for me, since I tend to go for unconventionally attractive men with more, shall we say, more striking features instead (EARS ♥).

I'm just tempted to say that Arthur is polished cubic zirconia, whereas Merlin's a diamond in the rough, but I fear Tan may tackle me if I do! *hides*