I can see the Nash comparable, I didn't see it at first...
No one is gonna rank Brees over Manning. They were only 3 football years apart (Manning drafted in '98, Brees in '01) and we saw their careers overlap for 15 seasons. They are squarely the same era of QB. Brees had about a 3-season run where you can definitely argue he was Manning's equal, '09 to '11. The issue is we saw both of their careers before '09 and it isnt close, and we saw Manning's comeback run in '12 thru '14, there's too much on the board to put Brees on Manning's level...
Rodgers is a much more digestible comparison, though it does feel like Rodgers is putting distance on it. They are only 4 years apart but in actuality Rodgers career not beginning until '08, they've shared 13 seasons together. Rodgers almost feels like he's of the '10s era, he isn't truly of the Manning/Brady/Brees era, those guys are way older than him (football years), he's more of the Wilson/Ryan/Flacco/Cam era of quarterbacks. And just like with Manning, there absolutely is a window where a)Brees was better than Rodgers---->in '09, following Brees' MVP-worthy season and subsequent Super Bowl, nobody was saying "Aaron Rodgers is a better quarterback than Drew Brees"...
And b)that 2011 MVP race was alot more hotly debated than people want to remember here 9+ years later. That was really the first time you started hearing Rodgers vs Brees debate and at the time, while that's when the whole "Rodgers may be the most gifted thrower of the football" talk began, there was no consensus Rodgers was better than Brees. Brees was squarely in his prime and putting up historic numbers on a perennial contender, the only thing '11 changed is it vaulted Rodgers into the conversation with the three OGs...
As I mentioned upthread, at this point Rodgers has played 13 years and its fairly clear he's jumped Brees, and it feels like he's also putting some distance between them, but it certainly wasn't always that way; he wasnt always better than Brees the way Manning was always better than Brees. The separation and subsequent consensus favoring of Rodgers over Brees came in the 2012-16 window when Brees missed the playoffs 4/5 years and we saw Rodgers get back to two NFCCG's, win another MVP, lead a flawed Pack team to the postseason despite being hurt half the year, play thru various injuries, and carry multiple flawed Pack teams beyond their talent level while Brees was going 7-9 with similar talent. Somewhere in that window is when the consensus shifted to Rodgers over Brees but its never been by as much as Rodgers homers want folks to believe...