I see the
Kwisatz Haderach as the combination of all the
mental disciplines used throughout the
Imperium.
Muad'Dib had the
prana-bindu training of the
Bene Gesserit. He was also a
Truthsayer. He had the prescience of a
Guild Navigator and the intellectual capabilities of a
Mentat. He also had the
Other Memory of a
Reverend Mother, and was the
Fremen lisan al-Gaib (the "
Voice From the Outer World").
Muad'Dib was the culmination of all these disciplines.
There are a few other characters in the
Dune novels I think either actual
Kwisatz Haderachs, or at least, good candidates: