Envision yourself as a typical teenager in 1977. It had been raining all about and your family had decided to remain home. You had been fortunate enough to own an Atari VCS/2600 and the 9 launch titles- of those titles, which would you most likely play?
I was that teenager in the fall of 1977. My family bought every launch title as they became available through Sears (less Math).
I played each single player game to death. And I would have friends over to play the four player games .. Yes we did buy a second set of paddles in 1977.
If I have to choose .. It's still Indy 500 (Race) for both the single and the two player games.