My personal preference, from the technological and aesthetic point of view, will be the 34, and I say this although I own a 33.
Which one is the fastest? On stock power per se, the 32 should be the fastest as it is the lightest and most nimble. The 34 is however probably more drivable in town and the real world as it has more torque at lower rpm. But hell, no GTR is gonna stay unmodded for long. On that assumption, it all depends on the mods, really. On the track, I'd whacked a 32 and 34 but I'd also been whacked by a 32 and 34 with more power than mine. So, really, we can't say which one is the best.
I have yet to hear or read about a test on all 3 cars in stock form. That would be interesting.