Haha, I never even listed any ‘realist’c artists. Even if we have G1, they’re still too stylized for me to call them realistic. I’m more of a sucker for luna-style stylization atm, but not much more realistic than cartoonlion. I was just throwing whatever examples I remember of.

At this point I’m really noticing you are leaning towards more horse/realism. That’s not really what I’m going for, stylized but still more like the show than actual horses is what I want.
 
I mean, the standard MLP Mare has nothing like a real horse’s face, they actually remind me more of cats at times.

May as well add that it probably shouldn’t hurt to look at other artist’s ways to stylizing horses. Off the top of my head, G1, Celestia/Luna, and cartoonlion comes to mind, but there are probably more.

That’s because the style of the standard mare has those really small snouts to go for a cute look. Big eyes + small nose = cute. There’s a reason why teddy bears are made with big eyes and small nose instead of big nose and small eyes. The show-style mare style works because of cute factor.

Though I forgot to add, if you look at the show style, mares have that round curve like these here. But it doesn’t really look good on the larger snouts it seems.

You are absolutely right, What I should really do is make the jaw more boxy at the front, but still not as much as the Stallion jaw, I also considered giving them both that bulk near where the muscles would be, like the princesses have.

I’m seeing more than just a steeper curve on top of the snout. Their jaws are curved differently; stallion more straight and mare more curved, but curved in a way they are no longer horse-like to me.
 
I wonder how it would turn out if we have a jaw that curved down, up, then down again?
 
Real horses seem to have a large bulge in their lower jaw, and Luna and Celestia’s jaw style seems to have included that bulge in their design to look a bit like a horse, but they seemed to have cleverly found a way to still make them look very feminine. You could probably find a way to have a large snout that looks feminine but still look pretty mare-ish. Just throwing that thought out there.

I actually think the lack of expressiveness is more the fact I tried to keep it mostly muted, a neutral face. Though the smaller eyes will have one effect, it reduces the emphasis the eyes make on the actual shape and the exaggeration of symmetry.
 
My proportions do change a bit don’t they? That’s something I have to work on, consistency is one thing I’m really struggling with.
 
Ultimately the Mare’s face is just the Stallion’s but slimmed down with a steeper curve to the bridge of the snout. At least that’s what I was going for, not sure what to do to make it look any more like that if it doesn’t.

Wait, I take back what I said below. Going for smaller eyes doesn’t make them lose their expressiveness itself as I’ve seen anime/semirealistic styles that seem to pull this off just fine. I think it’s just what I’m seeing isn’t very expressive to begin with. I think there are other expressions you can use that can start to breathe life into your works. What you have here are stern looking eyes and really stiff mouths.

Going for smaller eyes just makes them lose their expressiveness for me. I’m also seeing your proportions vary across different head poses.
 
IMO, I’m thinking it might be worth looking at real horses and try to stylize that. Stylizing what’s already stylized could get you to stray a bit far from the original animal I would think. I think the gist of what you’re aiming for the stallion is fine, but the mare doesn’t seem to resemble anything to me…