Probably Josh Norman, but I've yet to see him play in a meaningful game as a Redskin.
Outside of Norman, I'd go with Jordan Reed. He's not the most... willing blocker, but he absolutely makes the passing game. He might be the best route running tight end in the entire league at the moment.
The easy answer is AP, but I'm going to say Harrison Smith. The guy opens up the defense so much with his all around play. He can lay a bone-crushing hit one play, come up with an incredibly athletic interception the next. This guy is incredible. Others in consideration: Anthony Barr, Xavier Rhodes, Linval Joseph