The best current Prestige is whichever one you play best with. The Pro does make more spin a bit more easily. It's also the most powerful of the lot. Depending on the way you hit, this may or may not be the best option. For me, the Pro was a tad difficult to control if I wanted to hit a cleaner ball. It basically meant that I had to string a bit higher than I'd like. I also found it a bit less forgiving on off-center hits--there's just more off-center area in its larger frame.
On the other hand, I find the Mid has a very large sweet spot relative to the size of the frame. Even shots hit well towards the edges of the frame are very easy to put in the court. In general, I find it much easier to make spin with the current Mid versus iterations of previous generations, all the way back to the Prestige 600. Adding a leather grip makes it even more head light, which I find helps me make crazy amounts of spin if I want to. YMMV.