right now, i'd say nnamdi or champ.
i'd put t-new in your list, if he was healthy. but he hasn't been 100% healthy the last year and a half. and he's gotten burnt terribly bad this whole year, especially against the redskins.
cro had an amazing season last year, with 10 picks, this year, he isn't doing as well. but it's hard to pull off a better year than the season he had last year...
toine winfield is hella underrated though, probably the hardest hitting corner in the league...