He's accomplished the most, because he's the NFL QB equivilant of a trust fund kid. He's had a completely unparrelleed support system for his entire career, in a way that nobody else comes close to. I think there's an argument to be made that QBs like Rodgers, Brees, Peyton, could've accomplished about as much, if they'd played for an organization as great as the Pats, instead of Brady. However, Brady still has to be considered the best, because while we can guess what others would've done given his opportunity, the thing we can't do, is take for granted what they would've done. Maybe Brady would be no where near the top if he hadn't been lucky enough to get into this situation, but that's not the world we live in, and we can't give more credence to what we guess might've happened, than what has actually happened.