Montana Was Better
Lots of guys on talk radio now say Brady is the best QB of all time. This is total recency bias.
Montana played in a much tougher era for QBs and still prevailed.
All you need to know about QBs in the Brady era is to look at Manning, Brees, Rodgers, Eli, etc., and realize Brady wasn't even the best QB in the league for many of the years he played.
Montana had no peer.
Brady is great, but he rides the coattails of Belichick. One could say the same of Montana and Walsh, perhaps, but Montana won a Super Bowl without Walsh and took the KC Chiefs to the AFC Championship game and the playoffs, still performing his late game heroics late into his career. On the flipside, the one year Brady went down, the Pats were still 11-5 with a career backup in Matt Cassel.
IMO, Montana was not only the best QB of all time, but the best player. People talk about "clutch" players, but there was no one - not Jordan, not Kobe, not Brady, no one -- who was calmer, cooler, and better in the clutch than Montana. Go look at the tape.
SIDE NOTE: I actually think there's a better argument that Manning in a superior QB to Montana because he did a lot more - basically functioning as his own offensive coordinator - if you went by overall, regular season metrics. Manning's flaw, of course, is his inferior postseason record where he can't hold a candle to Montana (or Brady).