According to T-Pain, the pioneer of Auto-Tune Kanye West uses the software incorrectly. There are many ways to use Auto-Tune. One is non-obvious slight vocal correction and the second is the very obvious robotic like vocals as we are used to from T-Pain. However is it not as straightforward as many think, there are a lot of settings to pay attention to and some tweaking.
According to T-Pain the only other artists that have got it sounding just right are Chris Brown and Jamie Foxx.
T-Pain also mentions that in the album 808s & heartbreaks he got it right because he had proper help.