wherever you look, rule of thumb, a horse that is older, like 10-12 years old, are going to be more calm, better mannered. I would suggest that every horse you consider buying for this be tested extensively. For example, can you pull; his tail, and you crawl under him, can you ride him backwards, can you sit behind the saddle in the kidney "tickle spot"? Can you fling a burlap sack around without startling him. Is he difficult to get into a full gallop? This would be a good thing. The best kid horse I ever had, was nicknamed "catsup" because he was slow when I rode with my friends they always had to stop and wait for me and him to catch up, He was great with kids. They would crawl up his legs to get on him and he would just stand there and wait for them to get there...I miss him a lot.