I wouldn't say that the girls are the best this year. I actually felt that Cher Lloyd was the most original contestant of the whole lot, however, given that she can't handle pressure (probably due to her age), its unlikely she will have the staying power to make it all the way through.
For me, the (male) painter (at this point of the show), is the most complete singer, so I would say at this point he is the most likely to win.
The black girl (who always cries), is also a good singer, however, personally, when I listen to a song or watch a singer perform, the last thing I want is to see them cry. The best performances are those that the singer is enjoying with the audience. Perhaps if I were having a funeral reception, I would have the black girl sing, but other than that...no thanks.