I'm gonna call it 2010 playoffs through 2019 regular season (so this year's playoffs don't count).
Peyton: 5 years, 1,893-2,849 (66.4%), 21,812 yds, 7.7 y/a, 173 td, 70 int, 99.4 rating
2 SB appearances, 1 SB title, 4 pro bowls, 2 all-pro, 2 MVP
Brees: 10 years, 4,170-5,997 (69.5%), 46,770 yds, 7.8 y/a, 345 td, 127 int, 102.9 rating
1 SB appearance, 1 SB title, 9 pro bowls
Rodgers: 10 years, 3,187-4,925 (64.7%), 38,145 yds, 7.7 y/a, 305 td, 63 int, 103.6 rating
1 SB appearance, 1 SB title, 7 pro bowls, 2 all-pro, 2 MVP
Very tough call. I'd say Manning over his 5 years was the best, but you can't go only 5 years and win player of the decade (non-Brady edition) unless those 5 years were so over the top dominant compared to your competitors that it's just not even close. Think Pedro Martinez-level dominance in 1999-2000. This...isn't that. Manning was great, but missing 5 years kills his candidacy, IMO. So between Brees and Rodgers, it's close. I'd go with Rodgers, based on 2 all-pros, 2 mvps, a better passer rating, and doing it while playing outdoors in Green Bay, rather than in the comforts of the Dome and playing in the south.