Yearling
Buying yearlings is best left to experts, but I would go more on how it looked in baby pics than siblings who can vary A LOT…just look at people and families you know. 25% of foals will end up less than the average of the parents, 50% will be the average of the parents and 25% will be better providing one is using really good breeding stock to start with. The long back and short neck may improve but probably not go away. Yearlings should look a little bit long legged. Rear end high is OK if its not too much…but buyer beware on this…many horses stay that way.
Very important is how does it move…loose and long or short and tight? It should have a LOT Of overtrack at the walk, 2-3 hoofprints or more. It should stop using its rear end like a cow horse and not jab its front lets into the ground. You want to see mini piroettes when it turns sharp in the canter. It should be on the ‘correct lead’ and change leads cleanly when it runs and plays and not be disunited…How it moves is more important that how it looks at all ages if its going to be a sport horse. If it is going to be a jumper put some poles on the ground or bigger obsticles…or watch how it take a ditch in the pasture…anything that is a mini test of athleticm and what your purpose for it will be.