I vote for pony. My first mount was a pony my sister and I shared when I was about 8 or so. He was very gentle. As we got better we both got our own ponies. My next mount was a fairly green welsh small pony that I rode for a few years and did very well on and learned a lot. She got melanoma and we retired her to a big farm. Next I got a great medium seasoned show pony and cleaned up on our little circuit. My sister got a large about the same time and we didn't have to compete against each other as we were in different divisions.
I really think it depends on the kid and the mounts available. However I love ponies and still ride them at 41.
I think it all depends on the kid and the pony. I've seen young kids get really frustrated by pony "attitude," and absolutely flourish as riders and horsepeople when they were put on a horse. I've also seen ponies really take care of timid riders who were intimidated by a larger horse, and help those riders gain confidence and skill.
I personally love ponies. All I have ever owned were large ponies (more horse-type comformation, one 14.1 hands, one 14 hands even), and both of their personalties are wonderful blends of pony tenacity and sense, and horse amiability (I know I'm generalizing a bit here, sorry). Plus, they're just plain closer to the ground, lol.
I started with a pony. Got him when I was three (I just posted an ancient photo of us on another thread) and had him until I was twelve. I learned A LOT with him. I would just jump on him with no saddle or bridle in rain, shine, sleet or snow! I'm glad I started with a pony...however, I started my own girls with a pony and they just never took to riding. I think Scoutrider hit the nail on the head. Even though he was gentle 95% of the time and very lazy they got frustrated by the pony attitude. If I were to do it all over again with them, I'd go with an older, dead broke horse.
I never had the opportunity to ride a pony. I have always been around regular sized horses. My first mount was a miniature burro that was given to us as a gift. He was a 3 year old jack and I was 3 also. He was the first animal to ever buck me off. LOL *sigh* good memories. Anyway, he taught me more than I think any other animal would have. If it had not been for him, I don't know that I would have been able to handle a 16hh QH when I was 4. I agree though, it really depends on the particular child and the particular pony. Some children get frustrated and discouraged by a stubborn mount and other kids thrive on a stubborn horse or pony seeing them as a challenge to learn from and overcome.
Just for fun, here is a really old pic of me an him.
My very first time on a horse(not pony) was when I got diamond. And he is 15.2 so he aint no pony lol. I have had 4 ponies in the past tho, I think horse seem to be more eaven temperent. Ponies seem to have meen aditudes