I would go with a gelding. Tho there are exceptions to all genders, geldings are usually less tempermental.
As for for the breed of horse, it's a case to case basis. Quater Horses can make great first horses BUT you are tall and I think you would find it difficult to find a horse that suits you properly. You should look for an older horse that has done it all. Most older horses by this point arent affected by a green rider and will take you around the arena and around courses without problems.
My first horse was a 15 year old tb. Great first horse. Had done it all and was very patient with my many riding mistakes.