Just my opinion but I would say Super Mario Bros 1-3.
I know the first thought is that 2 was not similar to 1 and 3 but it was still a good game. And I believe Mario 3 was so good it ended up being one of the greatest games ever.
Even something like Kingdom Hearts where you can travel to each Superheroes World.
Drop DC universe MMO. It was good but past it’s time.
Give us a damn good DC RPG game where we can play as each character. I feel this will never happen because it’s too good to be true or if it does it will be live service and get ruined.
