I think you have an arab/qh. His conformation looks very typical of this crossing, and I've seen a few of them. I've also seen a few mustangs, and while you see almost ANYTHING come out of a mustang herd now, kigers still seem to have a standard. He does not look kiger at all to me. Not in the slightest. EVERYTHING about him almost (for lack of other words) screams refined breeding to me. He's a very nice horse! Mustangs (though I love them to bits, they are my favorites after PRE horses) are much more rugged.
He could be a paint/tb as paints are simply quarter horses with color. That's my second guess (appendix qh). But first is definitely arab quarter horse. He looks just like one I used to know, well similar.