JW's mechanics have changed quite a bit. His footwork has gotten a lot better, he used to throw off balance a lot even when he was set. That slant throw he was balanced throughout, also looks like he has brought the ball a little closer to the top of his shoulder than last year.
To be honest all 3 look good, I think we are in good shape regardless. I think JW has an edge because he seems like a gamer to me, whereas Chelf is a little more passive.