Join Date: Aug 2009
Location: New South Wales, Australia
Horses temperament is often pretty set regardless of age. While they do mellow in their later years, you can still get a horse that is very hyper, energetic, nervous etc in their teens or twenties, just like you can get a horse that seems dead quiet at three. So look for a horse with a right temperament, rather than just age.
Saying that, I would get one probably at least six or older, as younger than that they can still have the youthful silliness, and their temperament might not be as obvious. However, ideally I wouldn't be getting anything under 8, with 8-12 the ideal range, maybe up to 14.