Which FINISHES Better, Rupes 15ES or 21ES Big Foot

Looking to complement my polishers and upgrade to a Rupes Big Foot. Already have a rotary for heavier cutting when needed. Now looking to upgrade my old PC orbital to the newer "long-through" orbital design and settling in on the Rupes brand. While not as aggressive as a rotary, I suspect the Rupes 21ES Big Foot will do a rather good job of cutting due to its longer-through, but which of the Rupes orbitals, the 21ES or the 15ES, will FINISH better? I am looking for the one that finishes better, anyone have experience with both? Phillip?

Thanks in advance for your input!

Cheers,
CG