Tough. Good QBs, but never exactly over-achieved. So many BAD QBs these days that they certainly stand out above most, though. I'd put Ben as the clear #1 out of that group, team has played at a high level for most of his run. Eli has the 2 rings against the Patriots, but played to fairly mediocre results for most of his years. Rivers feels like he should have done more with his talent, but really only made that one run that I can remember, and it was a quick out. On a different team, feel like he'd have done better, I dunno.
Given the way the NFL has been trending, there will certainly be less decent QBs when those 3 quit. Have a hard time using them to define the era, though, outside of maybe Ben. And even then, it was really the Manning and Brady show, with Ben as a decent third act. And then there's Rodgers sort of straddling the timeline between Manning/Brady and the slightly younger crowd we're talking about. He's probably about the same age as the younger guys (when was he drafted again?) but definitely better.