I'd find a happy tempered, calm old horse who's breed isn't known for flipping out at the rock in the road, and doesn't have to be worked with EVERY DAY to keep them the same gentle and willing-minded horse. I've found Quarter horses and Quarter Ponys...(and other breeds like alot of Draft horses; though you probably wouldn't be interested in a huge draft horse!) to have a good reputation for being fairly sane. I wouldn't want most Thoroughbreds or Arabians (MOST of them) because they have the reputation for being a bit more high strung and I have found from owning, and personal experience that I didn't have to teach a Quarter Horse something as many times as a TB or Arab.

Quarter horses are also easy keepers. They can keep their weight on wonderfully. My geldings are not on any grain, just pasture, and in the winter they get hay. I have never had a weight problem from any of them. My stallion is getting some grain, but also my broodmares and that is because they are carrying foals and I like them to have more nutrients.

OF COURSE as someone stated previously, every horse is different and you could find a horse that's breed is known for being a high-strung dingbat and the horse is the total opposite.

I hope no one gets offended by my post! I didn't mean any offense at all