I’m still thinking about this because I think I have played them all, most when they were new.
Seaquest is awesome. Chopper Command, Enduro, Dragster, Grand Prix, Megamania, Barnstorming… many of those were so simple and yet provided hours of score chasing entertainment.
H.E.R.O. may be the best. I actually won some free swag on Gametap years ago by having the highest score in one of their contests. I played that game a LOT.
It was definitely an amazing era on the VCS/2600. Activision brought something it really needed at the time as Atari was prolific then but quality had dropped off.