It's the one called "GRect". Uh, I'll explain it here.
Essentially there are two varieties of pitch shifting extant in modern music, those being granular pitch shifting, as well as rectification. There are other methods by which we can impart a pitch, vocoding and the like, but if we're talking about pitch shifting strictly as the idea of changing a given sound's pitch hopefully without affecting any other characteristics, that's all there is.
Now, the VAST majority of the pitch shifters you see in VSTs today are granular, which is to say they take very very small pieces of sound and shift each of those individually. They're very flexible, by which I mean for the most part I can shift something to any note in the chromatic scale with relative ease, but with that in mind, they do tend to color the sound, either ending up with a whiney, chipmunkey sort of sound on the higher end, or else making everything muddy and darth-vaderish further down. THERE IS ANOTHER WAY.
A RECTIFIER (the device in question) does not shift pitch by analyzing grains of sound, instead, it actually splits the wave in half horizontally, then folds it over and normalizes the result, thereby DOUBLING THE FREQUENCY.
The result is a lot more natural of a sound, which is fantastic for drums and the like, and excites a lot of the higher frequencies in a big way, while preserving the character of the low end. Which is to say, if you're looking for "fat" sound, look to this VST. To my knowledge, this is the ONLY VST that actually does full-wave rectification, and honestly the results speak for themselves. I really encourage you to give it a try.
