How is Shishi sonson "stronger" than Onigiri? Shishi is a blitz move focused on agility/speed.
His top 3 moves are Ashura > Sanzen > Onigiri. Mihawk battle showed this.
No Oni giri failed on Mr1 so he had to use Shi Shi Son Son.
When it comes to raw damage output Shi Shi Son Son is next only to ISDS bar Ashura.
Shi Shi Son Son is so strong Zoro had to particularly comment on it, it's much stronger attack.
Zoro had already tried Oni Giri, if it was effective he'd use it again.
Kaido no sold Oni Giri and Tatsumaki fucked him up.
The way its portrayed Onigiri, Ashura > ISDS > shi Shi son son > Hiryu Kaen > Tatsumaki > Oni Giri.
Zoro even wanted to use Oni Gri to break Kakus tekkai and that's the only move Kaku bothered blocking.
Shi Shi Son Son was also the move to be able to do some damage to Kuma pre TS
Its denying manga to try to put Oni Giri above Shi Shi Son Son