Say whatever you will. Seto Kaiba is basically the best character I have ever seen in anime and manga. Not as a matter of having the best writing, but just being way too fucking cool. He's so intelligent and has so much ego that he basically developed something akin to digital godhood. He did this over card games, because he couldn't stand losing.

He developed portable hologram display systems. He threw a tournament in a whole city, on a blimp, and on a private island that he then blew up. He built a space station to house an ancient relic and a computer system to scan it to solve its puzzle. He send his own consciousness to the afterlife just to battle his rival one more time.

What other characters can you think of that have the fucking balls to pull this kind of shit off?