There's a ton to take into consideration when declaring QB's over the other, it takes a lot of research for major proclamations.
I've done considerable "Peyton Manning vs. Tom Brady" research and discussion... and I maintain that while Brady has more rings, Peyton Manning was the superior QB who could move an offense and put points on the board. An example is that throughout their careers Brady averaged the 7th best defense per scoring against his team while Manning averaged the 17th, thus, Brady routinely had to do less to win. Manning had 5 MVP's (should have had 6) while Brady certainly had his years but almost never was the most high-octane QB in the league.
I'm not saying rings mean nothing, but they're a team stat, not a QB stat. This isn't the NBA where a player can D-up and have any sort of control over what the other offense does.
As far as the list, without doing an analysis, there are a few factors. Steve Young was dominant but not for what is considered a long period of time, he led the reighns in SF for like 7-8 years with 1 SB, 2 MVP's and 3 1st team All-Pro nods.
My list of these players?
1. Joe Montana
2. Dan Marino
3. Steve Young
4. John Elway/Brett Favre (tie)
5. Troy Aikman