I missed out Steve Young. He deserves a place on that list. Maybe not the top 10, though. And I mentioned Manning (the Peyton reference...)
No, the rankings aren't arbitrary but they're misleading to the average football fan. Before I had viewed the site, I assumed the usual HoF qbs would make up the top 10 or so and then the others would fill out the page. But to see players like Romo and Rivers is the top 10 clearly shows that the stat is flawed. Although it tries to measure QB performance as objectively as possible, it's missing one of the biggest stats in football: wins. There should be a minimum amount of games played condition that eliminates the newbies like Romo, Rivers and Culter. I don't know, 75 games started?
I agree with stupeedo. Brady's had one season with the type of receivers that Manning has been blessed with his whole career and explodes in record-breaking fashion. He's also been the qb for the team that set the record for most consecutive wins and the record for second-most consecutive wins by a team (21 and 18, iirc). 9 consecutive playoffs wins only adds to his resume as a big-game player and this was accomplished at a time when he had the corpse of Troy Brown to throw to. Enough, anyway. This debate has no right or wrong answer. I hope Brady comes back in top condition next season and I hope Peyton starts next season healthy. They're awesome to watch.