I literally can't remember 2 at the moment.
Anyway, SMB 1 changed gaming, imo. I still remember buying an Atari 7800 in probably 1984 and a neighbor laughing at me because he bought a Nintendo, which I'd never heard of.
I went to a friends house and saw SMB and was absolutely blown away. My parents quickly learned how much of a nag I could be and I finally got my Nintendo and played SMB 1 nonstop.
I'll never forget when I first beat the game and called my best friend to tell him.
Then the next challenge was to beat the game WITHOUT WARPING. That was much harder, but I finally achieved that as well.
What a game.
SMB 3 was probably better overall, but I can't ever rank it first. If you were there when one first came out, I imagine you feel the same.