Yamauchi, by far.

Without Yamauchi there is no Nintendo

Yamauchi transformed the corporation far more than Iwata. But Yamauchi was far more of a scumbag than Iwata ever could be. Yamauchi was greedy and arrogant.
I ultimately say Iwata is better because even if he had a lot of ups and downs and wasn't the most effective leader, he took a big paycut after a rough patch. That's true leadership. He also was a genius game programmer. Iwata is a much better person, and I say that's enough to give him the edge here.
I say that Furukawa has the potential to be the best CEO Nintendo has ever had. If he can keep up Nintendo's strengths and acknowledge its failings, he's gonna be great.

Yamauchi. I liked Iwata as person, but didn't like the direction Nintendo went with Wii and Wii U.

Hiroshi Yamauchi. The Nintendo of today wouldn't exist without him. A legend in the world of gaming.

Yamauchi by far. He took a tiny playing card company in Japan and made them a global billion dollar brand.

Both were pretty great. I don't even know who the current guy is. Might as well be AI.

You can tell a lot about a leader too in how they deal with hard times; Iwata may have presided over the Wii U/3DS slump, but in his final days he organized what would go on to be an earth-shattering comeback, as well as taking a personal pay cut when profits slowed rather than lay off workers.

Yamauchi by contrast seemed to dig his heels in when the going got tough; he oversaw Nintendo's dominance in the NES era and the SNES's victory in the 4th gen, but Nintendo's decline from industry leader in the 3rd/4th gen to basically irrelevant in the 6th gen also happened on his watch, and it was Iwata who ultimately reversed this downward spiral.

Nintendo was around for a long time before Yamauchi. He also had a lot less to do with Nintendo’s early video game fortunes than Gunpei Yokoi.

It’s also no surprise that after the downfall of Yokoi that Nintendo seemed to hit a steep decline, but were propped up by Yokoi’s most successful product, the Gameboy, for years after his fall, resignation, and death.

Hiroshi Yamauchi. imo it’s not even close.