We won't know who "won the trade" until we see how 9mm fits into the post-rebuild Sens' playoff performances.
That being said, if you use pure entertainment value as the sole determining factor, we won the trade. I hate watching Heatley play. He is a one note player. He waits to be set up. That's his game. Milan, on the other hand, plays a two way game, makes exciting plays on both ends of the ice, and almost has a Guy Lafleur flare when he breaks into the other team's zone. At the end of the day, he's much more fun to watch.