Which Horse To Choose For The Story?

I wanna make a story about a horse but, I am having a bit of trouble of choosing a horse to do a story with. The ideas for the story I have in mind is about a horse who has very much nervous at first coming home. The more the rider spend their time with the horse. The horse would be more comfortable and feel confident in itself and their rider. I been wanting to do a story like this. Just for fun.