I would pick Rupes over and over again.
Simply, they're a manufacturer. They make the tools, the pads, plates, and polishes. A great system to go along with great tools!
I've received great support from them, I've seen their tools operating locally in at least three high production shops in my area, and their innovations continue despite the popularity of the original BigFoot line up. They just introduces a forced action D/A, and a Rotary to their BigFoot family of tools... Along with optimized systems of pad/polishes to compliment the motion of the respective tool... To me, that's a commitment to the detailing industry, and for those of up wanting better results in less time, with more comfort. I absolutely love the company for this!
Outside of that, I imagine the two in question perform similarly. I would venture to speculate that the Griots system would be the more user friendly of the two, but I can't say for sure, as I'm unfamiliar with their line. The bottom line is that either of them are the state of the art as far as technology is concerned.