The orbital buffer because its the least aggressive tool for about the same job and results; less likely to make burning mistakes! I have a porter cable so I also buy my polish at autbody supply store's. Most polish sold elsewere are designed for hand. Using a hand polish with a machine will cause the polish to break down too quickly, and you won't get enough cutting action (borrowed from auto paint book). Un-like a reg. parts retail store, the guys at a pro supply place can help recomend the best machine polish for the job.
If you use it on the boat, bet your car(s), truck(s), etc will follow.