Couple thoughts...
1) Generally agree Eli wasn't elite...
2) Definitely agree his stats (all guys his era and on) have inflated numbers vs. those historically due to the changes in rules, and proliferation of passing attacks...
3) I think his durability, and being a legitimate upper 1/2 NFL starter for a long time does matter... being a 2x SB QB matters, beating the Pats twice matters...
4) Not 1st ball, but ultimate HOFer makes sense to me...
5) Re: Rivers having better numbers... at-least some consideration has to be given to it haven been easier for Rivers to play 1/2 his games in San Diego, vs. Manning in Jersey (winds of the Meadowlands).
6) On talent, Elway is an inner circle guy at QB imo.
San Diego is pretty breezy.
But sure, you can consider weather. One of the reasons I responded to Mike's comment was the garbage time remark, because I'm guessing that Eli's stats benefited more due to that considering the Chargers were the better regular season team.
Regarding beating the Pats twice, I mean we all watched those games and we know the primary reason why the Giants won those games. Their D line did a great job. Also give an assist in the first one to the most absurd catch ever. Going into those games, almost everyone thought the Giants offense would have to be better to win those games. I'm not saying he was bad, though to be clear.
There is something to getting to the Super Bowl of course, but he, nor the teams were special in those regular seasons, and he didn't exactly go on a Flacco esque run in either of those postseasons either.