Outside of tech geeks, real people don't care about this. They care about the UX.
Just looking at numbers like this is a gross simplification.
The standard on iOS is to implement navigation buttons in software as needed. Done right, this is better UX, because different apps can provide different navigation buttons to support different navigation schemes.
iOS's One Button to Rule them All also behaves different ways in different contexts, but the way it behaves is fairly easy to learn because it's consistently linked to the screen's visual state.
In short, neither is terribly great UI. But I think this is one of those cases where which one is worse is entirely dependent on which one you're more used to.
Ended up with a Droid Incredible 2. She loves it.