Well, Nova has been money of late. As has Hughes. Colon has been floundering a bit but he is better than Burnett and Freddy has been solid all yr. Burnett is the obvious choice.
That being said, Nova has looked very solid since coming back from the minors, and the main reason is the development of his slider. He used to have a loopy slider in the minors that wasnt terribly useful. He was good enough to get by on his big curve, good change and hard FB. But after coming to the bigs, he didnt have a put away pitch. Now, that slider is something the hitters need to keep an eye out for and he is using it in strikeout situations. He'll always be more of a contact pitcher due to his heavy 2 seamer and his good location, but the slidepiece has given him a strikeout pitch he can use when in a jam.