Anyone who thinks a horse is happier being a stallion is simply uninformed. I don't care how well trained they are, they are still a liability legally and personally. They can never reach their full potential as a family horse as long as they are intact.
I gelded a 20 year old stallion and he made the best lesson horse I have ever owned. He was a Palomino parade horse that had been everywhere from the Rose Parade to Madison Square Garden. He was impeccably trained, but his owner died, the 'stable boy' that cared for him inherited him, he was sent to prison and that boy's mother called to see if I wanted him. She was going to have him put down. I drove 800 miles straight through to save him. He had already lost 300 to 400 pounds in her care. I knew what a wonderful horse he was. He made the most incredible gelding. He taught too many children to count over the next 13 years. [We rode him and loved him until he was 33.] They all learned how to ride on 'Lucky' and none of that would have been possible if I had not had him gelded.