No particular breed. The best horse for you will depend on your knowledge and experience and the horse's attitude and training. In general terms, the less you know, the more the horse needs to know since green rider + green horse = hospital. If you are experienced, then it's a matter of what you are looking to do with the horse. Trail ride? Show? Mounted shooting? Etc.
I love my spotted saddle horse. But some breed of horses are more stubborn. Best to find an older, more sound horse to start with, but it also comes down to training and personality. I started out with a green broke horse and he was wonderful.
It completely depends on your experience and what you're looking to do! If you aren't very experienced, get a slightly older calmer horse with plenty of experience to increase your confidence and to help teach you. If you are very experienced, you can try getting a more green horse that you can work on training. If you are looking to show, make sure you get a horse that has experience showing. If you want to do things such as cross country, jumping, dressage, trail rides, or riding near cars, make sure that the horse you buy has experience with those things and won't react in unpredictable ways. Quarter horses are very good all around horses, along with Appaloosas, Canadian cutting horses, Colorado rangers, Irish hunters or Irish sport horses, paints, and warmbloods. If you are smaller and looking for a pony, quarter ponies, connemaras, haflingers, caspians, fell ponies, new forest ponies, pony of the America's, and welsh ponies are all great beginner ponies.