I am pretty darned sure that my mare shows affection for me, and that it's not just cupboard love. She'll follow me around like a dog while I'm setting up jumps, and she whickers to me when I walk in the barn. When I'm grooming her she "talks" to me - she'll watch what I'm doing, and make little comments, and nuzzle me. And she will do things for me (mostly galloping and jumping) that she simply won't do for anybody else. My trainer uses her for the beginners because she's so dead-set reliable, and if somebody sees me riding her in a lesson they're like, "THAT's Gracie?" because she looks like a completely different horse. I really believe she understands and adjusts her behavior to the skill level of her rider. She is a particularly people-pleasing horse.
On the other hand, this other mare pinned her ears the first time I walked up to her stall. Maybe I look like (or smell like) somebody who Done Her Wrong.