I was surprised by how bad Aikman's TD-INT ratio was. So I took a closer look at the stats. His interception rate was actually not bad: 3.0%, which compares favorably to Favre's 3.5% and Elway's 3.1%. The "problem" is that Aikman threw fewer TD's than the others. But that's because Emmit Smith was a TD machine, so the Cowboys did not need to throw into the end zone as often as most teams. Also, the Cowboys were not a West Coast Offense team. Their whole system was more run-oriented.
In my own memory, Aikman was even more accurate than the numbers suggest because he was so good in the three years that the Cowboys won the Super Bowl. His numbers suffered at the beginning and end of his career, when he played for bad teams. Favre only played one year with a truly awful team (2005) and I don't think that ever happened to Elway.
I think Aikman was the perfect QB for those Cowboys teams. I would not make the assumption that all of those QB's that Zombie mentioned would've won three Super Bowls if they played for the Cowboys, and so what if they would have? That's a pretty darn good list. Randall Cunningham does not belong on it, and Phil Simms is borderline. The others are all Hall of Famers.
As for the QB's listed as "might haves," I would agree with Boomer and maybe Testaverde but it's hard for me to believe that Zombie is serious when he throws Rodney Peete and Scott Mitchell on there. If you include those guys you can include dozens of other guys. Maybe that was the point, but I don't buy it.
I also think it's possible that a Favre or Elway--Favre in particular--may not have fit in with that Cowboys team as well as Aikman and may have won fewer than three Super Bowls. There's no way to know, of course. It's beyond hypothetical.
The main reason I put Aikman below Montana, Favre, Young, and Elway is that he lacked mobility. I really think that in terms of intelligence, arm strength, and accuracy, he was right up there with those guys, however. Overall, I would put Aikman in with Kelly and Moon. His numbers are less impressive than theirs, though, because they played in wide-open offenses and Aikman played in a conservative offense.