1) Johnny Unitas
2) Joe Montana
3) Terry Bradshaw
4) Dan Marino
5) John Elway
6) Troy Aikman
7) Roger Staubach
8) Steve Young
9) Bart Starr
10) Brett Favre
11) Joe Theisman
12) Jim Plunkett
13) Fran Tarkenton
14) Bob Griese
15) Warren Moon
16) Tom Brady
17) Rich Gannon
18) Peyton Manning
19) Sammy Baugh
20) Mark Rypken
Actually, Gannon's hella-underrated. His career stats are startlingly good, considering he flew under the radar for most of his career. And he did have that awesome MVP season in Oakland in...what was it, '02?
In any case, if I were making a top 20 list, he'd probably be on it.
But yeah, not ahead of Manning.
....
Also, Otto Graham isn't on the list. If you have older guys like Unitas and Baugh, Otto should be ahead of them both based on accomplishments and numbers. And as for Unitas at #1, anyone who tells you that is either over 60 or deluded. He would compete with some of today's QB's, but neither his accomplishments nor his stats nor his dominance of the era compares with MANY others on that list.
Gannon is 9th or 10th (somewhere in there) all-time in rushing TDs for a QB, 3th all-time among retired QBs in TD/INT ratio with a minimum 1000 attempts (His rate is 1.73 TD per INT, just ahead of Dan Marino). Only Brady and Manning are above him among active QBs (possibly McNabb...I haven't run the numbers on him). He finished with and MVP, 180 TDs, about 28,000 yds, and a QB Rating of 84.7...which is higher than many of the QBs on that list, including Starr, Griese, Aikman, Bradshaw, Moon, Dan Fouts, Tarkenton, Staubach, Jim Kelly, Elway, Unitas, Plunkett and Namath.