These are my thought about your list:
1. Aaron Rodgers - Best, but still holds the ball too long and takes negative plays. On the plus side, has the ability to make up for those plays. Outstanding offensive talent around him, but an average line that has been decimated by injuries. They will be better this year.
2. Tom Brady - Winner, and best OL in the game. He was average when all of his offensive weapons went down, or were rookies, but THAT system is built to win, and very sustainable.
3. Peyton Manning
4. Drew Brees - Think you nailed the top 4.
5. Phil Rivers - In the right system, with the right tools around him, he is a good QB, but seems too high for him. See the season previous to this, and what a difference a good OC, and better OL make.
6. Ben Roethlisberger - A winner on the field. Competitor. Holds the ball too long, and has suffered from an average to below average running game that just got better last year. Off the field....
7. Tony Romo - He's just not a winner. Sorry, but that means a lot to me. He has choked on the big stage, more than once. Stat wise, good QB.
8. Andrew Luck - He's not here yet, as shown in the playoffs, and what happens when teams get to him, see Rams.
Here is a list of QB's I would rank close to Bradford, still better, but just by a hair:
1. Russel Wilson - Super talent around him, extends plays, but does read the field well. I think you got him in about the right place.
2. Colin Kaepernick - Until he can read a defense, and not just take off with his God given ability, he can be game planned, if you have the right defensive personnel. We have, and we do.
3. Joe Flacco - I think Joe is a decent QB, who seems to miss a lot of plays on the field, and the offense completely disappears at times. I don't know if it's him, or his OC. Good talent around him on both sides of the ball. Very good arm talent, who makes some questionable throws at times.
4. Andy Dalton - Tons of talent on that team. One of the best receivers in the game. Plays different than Tony Romo, except that he can't find a way to win, when teams ratchet up the stakes, or in the playoffs.
5. Cam Newton - Think he should be higher. He's better than Kaep, he's used to be what Kaep is now. Hate his attitude, and his team may grow weary of him.
6. Nick Foles - Not enough games under his belt yet, so defenses will now have a better understanding of who, and what he is now. If he continues his current path, could be moving up quickly.
Here is where Bradford goes - Don't know what he can do in the playoffs, so it's hard to give him a grade. Great arm talent. Smart decision maker. Underrated athlete. Has never played with a lot of offensive talent around him, but that is changing. Still doesn't have an established #1 receiver, or veteran receivers until now, if Britt sticks, and Pettis can be a better player. Has a running game around him now, and that looks like for the long haul. Good defense, which should be even better this year. Coming off knee surgery. I think he will move up this list anyway. I think he will be considered in the top 10 this year. He's top 15 now.
So that means I would have Bradford ranked at #15 out of all the starters. He's ahead of the likes of RG3, Alex Smith, Matt Ryan, Jay Cutler, and all the others (in my eyes). I could go back and forth on having a few ranked ahead of Bradford, like Dalton and Cam, but the others are pretty set in stone. I think that is fair.
Yes it pains me to put Wilson and Kaepernick above Bradford, but I just can't justify putting Sam ahead of them considering what the other two have accomplished ("team" debate aside). I don't think you can't put team arguments aside, they are all relative to how a QB does, and football is a team game. I will admit that those factors make it extremely hard to rate an individual player in a team game. It really can't be done fairly. Defense, and special teams factor in too, as well as specific units, like WR's, and OL's, and OC's.