The best horse for a beginner rider is a horse that is older and experienced. An appropriate horse for a beginner should be even tempered, easy to handle on the ground, and well-trained to respond to a beginner rider's cues in the saddle. There is no perfect horse for a beginner in terms of an exact formula. Some horses might be beginner safe at several years old and with only a few months under saddle training, other horses may not be suitable for a beginner until they are in their teens and have many years of experience being ridden.
To find a horse for a beginner rider the best place to start is with a local riding stable, or a saddle club or pony club type organization. Be careful when shopping for a horse for a beginner, if you are beginner yourself you should always take a more experienced friend or a trainer with you to help you shop for a horse for a beginner. Make sure this person has nothing to gain from you buying an unsuitable horse. Before buying a horse for a beginner you should see the horse ridden by a beginner, or ride the horse yourself several times. There are lots of horses suitable for a beginner, but not every horse a seller claims is beginner's suitable actually it is. Be careful and remember rule number one -- you usually get what you pay for!