Okay, so first thing, your art is absolutely beautiful! I love the first, second, and fourth example the best as they really do have nice shading, coloring, background and the proportions are spot on!
As for the fifth I think maybe the horse could blend with the background a bit more if you know what I mean? It doesn’t exactly fit with the background. For number six I’d say maybe make the muzzle a tad thinner for the muzzle looks slightly off to me.
For 7, I have no words, just spot on!
I really do think you have amazing skills! P,ease keep up your amazing artwork