I personally think getting Jamison is huge since Cavs might not need to give up Hickson for him.
I think either Jamison or Murphy because they won't command a lot of shots like the other two. Murphy adds rebounds and is a nice post player, but he can also create problems by being able to step out and hit the 3. Jamison is similar to Murphy, and like you said, they can get either for cheaper than Amare.
Spreads the floor better and allows Shaq to be the guy inside. Doesnt demand the ball like Amare does to be effective (or as effective). murphy is an awful defender and Maggette should be there last option