The first one. And the second. Both were ho-hum affairs in which the Packers dominated AFL teams made from NFL thinnings and aftermarket draft candidates.
When the mutual draft between AFL/AFC and NFL/NFC matured, and vet players had some choice as to where they played, parity in the Super Bowl made it a true championship game. The foresight of Lamar Hunt came to fruition. The innovative offenses of Hank Schram's Chiefs teams and the San Diego Air Coryell attack made reverberations through the stodgy NFC. Offenses changed - and defenses had to counter. The game became more complex - and more exciting
The Namath guarantee of a victory in Super Bowl 3 was a sort of premature harbinger for what followed. While watching the game, Jets vs. Colts, I felt sure that if Colts coach Weeb Eubank started a then-recovered from injury Johnny Unitas instead of his replacement during recovery, Earl Morrall, that the Colts could have won decisively. When Unitas was inserted late, he scored the Colts only touchdown. The Jets won on one touchdown - and three field goals. Unitas showed - late - that he could have engineered more than enough points to win.
It wasn't meant to be. The AFC went on to win until the NFC put up an innovative offense of its own - Tom Landry's multiple formation/multiple look offense in Dallas.
Those early Super Bowls - three through seven - established what we see today: innovation from cross-pollenation you might call it. had its genesis in those early Super Bowls. And I've watched them all since the first one.