I'd venture to say that its almost an aesthetic decision between the two. If you want to go more in the direction of the even fender gaps the Prodrives are the way to go, if that isn't a priority, go with the STi. I think out of the box the edge is with the STi but a small tweek to alignment or swaybar easily brings the prodrive to the same level. You can't really go wrong with either.
Myles - perhaps you can dump a couple of your zeal pics and substitute them with a couple of good side shots of your car with the Pinks and a car with the Prodrives ( I think Mike-creowrx- has a couple of good shots). it would be great for reference for folks interested in either.