Brees has had a hell of a career but I've always considered him 3rd because he had several years where he flat out misses the playoffs. He needs more around him than Rodgers does to make the playoffs. Rodgers has been the highest paid QB since his SB which leaves the team less flexibility and still hasn't missed the playoffs since his 1st season starting.
You can make that argument though, Brees has years where he flat out dominates, but it hasn't been as consistent as Rodgers in my opinion. Big Ben and Eli aren't in that conversation to me. Eli has 2 rings but he's not even a hall of famer. There was never a time where Eli was a top 5 QB in the league. Ben is great but he stays hurt, especially lately. If he plays 16 games for these next 2/3 years I can see him in Brees/Rodgers territory because that offense is so good that they'll be in the AFC championship game before long.