I love how these posts always get off topic. I never wore a helmet growing up, and I was riding draft horses.... *shrugs*
OP, I think, that while asking others for advice and opinions is a good idea, you also need to be able to think for yourself and make up your own mind. Of course all of us are going to sing the praises of draft horses... I will tell you all day how amazing my Belgians are... But just because they are the right horses for us, doesn't mean they are for everyone. Most draft horses are calm and easy to handle, yes, but some can be high strung and pushy... Each horse as an individual, not just as the breed it represents is different. My 2 year old gelding is quite different than my 6 year old gelding. The 2 year old is very dominant to other horses and if allowed, he will be pushy with people, he takes a firm handler. My 6 year old is easy going and will plod along behind a toddler all day.
A draft is big enough to carry a heavier rider, but if you get a 17h horse, will you have the flexibility and strength to mount? (Not being rude, just pointing out something that might be an issue)...
Most cowboys weigh over 200lbs and they ride around on 15h Quarter Horses all day, every day. A short stocky QH with a short strong back and good legs will EASILY be able to carry you. As would a well built Arabian, a TWH, a Paint, an Appaloosa, a Halflinger, a Fjord, any Draft breed, a Cob... ETC... It really will not matter much on breed, and more on the build of the horse and whether it is suitable for a beginner.
I do HIGHLY reccomend you find a way to get riding lessons and find and equestrian mentor! I DO NOT suggest that you take on this endeavor with the just the knowledge you gain through books and google... Hands on experience is so much more important.
Good luck in school!