If aliens came to Earth and asked what is a video game, I would give them a Mario game.

I replay the Mario games a lot more than the Zelda games. But I often like my first playthrough of Zelda more than my first playthrough of Mario.

In most Mario games it is possible to jump back into a playthrough even after months or years and no matter where in the game I left it is fun to return. For a Zelda if I revisit I want to start over from the beginning. I guess it is the lack of a significant story in Mario games, even if I like story heavy games it does not lower Marios appeal for me, it simply makes the games more timeless.

This is a good point, and I can kind of relate; for example, BOTW is I feel one of the best games ever made, but I'm not sure I'll ever replay it just cos it doesn't seem like something that would lend itself to repeat playthroughs since the sense of discovery wouldn't be there second time around. I think the only Zelda games I've played through multiple times are Twilight Princess, (just cos I was so desperate for something to play when Twilight Princess HD came out during Wii U's dismal 2016) and Skyward Sword just out of nostalgia for my Uni days.

Meanwhile, Mario games I come back to time and time again, cos they're so much more "pick up and play".

I would give them Tetris, but I get your point

I don't know what to say to such comment...

Do you have any idea how big the Pokémon IP is?

You're missing the point of the entire thread. It's about quality. Not popularity. Which series is greater, not which series is more popular.

Any particular one?

Mario,

because there's no "Zelda Kart".

As per the OP, this is comparing only mainline entries, so no Mario Kart, Hyrule Warriors, etc.