Louis punched shorter, and had more variety with his right hand (Hooks and uppercuts were better). But when it comes down to P4P power in terms of the straight right hand I think Hearns edges it. Louis is the better puncher, though.
I agree with Pete, Technique and power Louis is unmatched but considering weight Hearns, no one P4P hits harder.
Who you like? Hagler? I respect that. I just think the shoulder leverage and quickness Tommy had is unmatched.