OK, I'm new here but I'm going to jump in anyway and express my never-to-be-humble opinion.
I don't much care what you think Ellery looks like (well, that's a lie...) but Ennis needs a good looking horse and that would be the buckskin or the dun. The one underneath the buckskin is a boodmare, her foal is behind her. I think the last one is just plain ragged looking. His horses have always been important to Ennis, so give him the best you've got. Nellie looks really good, but I've never cared for horses with stockings so I'll not even comment on Socks.(Sorry to be so pushy. I followed MaineWriter's link to Louise over here from Dave Cullen - as if that's a reason.)
For what it's worth.
Hi Tamarak -- How amusing you and I seem to share our priorities in the human vs equine character casting!
You have great observations! My reponses regarding the pictures I posted are:
1) Nellie is a part of the high end breeding that Wes has established, and thus would necessarily be a lot flashier than Ennis' horses.
2) Socks and Pal are both mares, I figure at some point either may have been bred.
3) That said, the sorrel does sort of look a little unkempt, but when I look closely I don't see a neglected horse at all - rather a typical working horse. Working horses don't usually get groomed for looks, just for function. Never the less, that photo undeniably was posted in haste as I was trying to find a light sorrel example to post.
I too am partial to buckskins, but my favorite is the Strawberry Roan -- (with the baby)
Monica