He looks a lot like my 3 yr old, who is a bay-going-gray.
In the winter he looks more bay, in the summer more black. Meanwhile, he keeps getting more and more white hair. So in the summer it's like he is turning black and getting whiter at the same time!
I like his summer coat best.
Does your guy have white hair in his tail? It looks like he might, but not as much as my gelding.