I find myself torn between wanting Rafa to lose to maximize Roger's chances of a title, and not wanting Raonic to win. I have nothing against Milos, but boy is he boring.
Some impressions after the first five games, with Milos up 3-2, Rafa to serve. Milos isn't getting a lot of first serves in and if he doesn't improve, Rafa will eventually get to him. While Milos has improved as a player, I don't think he has enough to beat Rafa without that first serve.
As for Rafa, I can see his age. He doesn't move like he did a few years ago. That said, he's a better player now than he's been for years. He looks steady, calm, and is playing smart. One thing I'm kind of glad to see for his sake is that he's not going for absolutely everything; he seems to be holding back more, not unlike we've seen Roger do the last few years, as if to save his body. At this level, which is probably equivalent to his B game in his prime, he can beat anyone except for a peak Novak. So I'm going to say that even if he doesn't win the AO, he's my favorite for Roland Garros.