I think if the horse has the passion and the ability almost any breed can be a great showjumper. You'll most commonly find warmbloods, and thouroughbreds. I've also seen a lot of amazing Standardbreds for jumpers. My friend's standardbred jumps 1.50m with ease. They're a bit harder to ride, and they require you to have a great seat but they have amazing hearts. Once you train them well, or find a well trained one they can be fantastic junpers. But thouroughbreds have great stamina... warmbloods jump well, move well, and are normally expensive. Good luck! Just find a horse you click with... the breed isn't very important.