Max, easily. If you can get over the lameness of Ted Kord getting shot in the face, pretty much everything they've done with Max has been awesome. He wasn't really necessary for the JLI to be great or for Giffen and DeMatteis' Justice League to be funny, so turning him into a villain works fine. It works well with his earliest appearances as a manipulative, possibly crooked agent for Booster, too.
Meanwhile, Osiris just... sucks.