Optimum Final Polish is a joy to work with and is SMAT. However, I just used PO85RD for the first time on my black BMW and was amazed at the results. It added a "pop" that may be subjective, but paint has never looked so rich. So if its a black car I would have to go with that. I didn't find it oily or to have an excessive work time as others have stated. In fact, I found you need to use a little more of it to keep the pad wet than other polishes. Don't know, but I was sure happy with the results.
Here are some IPhone pictures I took after using the PO85RD. It was a cloudy day, no sun. Car was already in great shape, just wanted to max out the gloss, also noticed
It seemed to add to reflectivity.