I don't really know. I like him!
I see suggestions of Morgan. Since he carries his tail and the inward points of his ears I suspect he is around 1/4 Arab. Probably some Mustang, possibly an appendix QH in there too.
I see that he has good withers.
Looks like you have a good eye for a horse.
I might be able to tell a little more with conformation photos of his side, front and rear. I can see why you bought him.
I still like him! With lots and lots of hill work at a walk and trot he should muscle up really good.
Keep these pictures so in a year you can take others and admire the progress you are going to make!
I would definately have to say I see the Arabian first, and the stockiness suggests some quarter horse...I think he has Arab ears :)
I'm more inclined to go with the mustang/quarter cross. He looks like there is more of a Spanish influence than arab. My mare is a mustang/quarter cross and her ears have a little bit more pronounced curve at the tip but very similar. Give him a couple more years to fill out and it might be easier to gauge.
Quarter Horse/Morgan, maybe? He sure is cute, I love his coloring.