Should i buy a mastiff or pitbull puppy?

im going to be moving out in a year or two and was wondering which breed of dog would be best to buy a Neapolitan mastiff or a blue pit bull? i am a very experienced dog owner ive been around and owned dogs all my life and i have personally raised at least three of them including a breed notorious for being stubborn so training will not be an issue . so what do you think is a better choice ? and please dont respond if you are just going to say adopt from a shelter i think thats a good cause and all but i want a purebred so i can know the temperament and energy levels of my dogs parents