Josh Hamilton, specifically 2010 Hardware Josh Hamilton. That dude was fun to watch when he was good. There aren't a ton of recent retirees in the game as legends, so this would be really cool I feel.
Since Musial has been added, my list now looks like this: Clemente, Maddux, Mays, and early 90’s Bonds. I’d love to play with Bonds based on his ‘93 season, rather than his early 2000’s Hulk phase. But I’m sure we will never see him added either way.