Whitebeard was the strongest person at Marineford IMO. Half-dead/half-head Whitebeard was smacking Akainu around, man was still terrifying even on his last legs.
But, as far as we've seen, Kaido is BY FAR the strongest character in this series. Big Mom took relatively no damage until she fought Law and Kid directly, and still lost before Kaido did, despite Kaido:
-Getting surprise shanked by the Scabbards
-Taking all of the Scabbards best attacks (as in willingly letting them attack him)
-Taking multiple powerful attacks from Law, Zoro, Kid, and Killer
-Fighting Luffy until Luffy was knocked out twice
-Fighting Yamato for a brief period as well
Kaido is the strongest character based on feats BY FAR, it's not even close right now, people who thought Kaido didn't do enough are just insane. People act like Kaido is weak because he doesn't kill often, but Kaido is only willing to kill if he deems it necessary. Even with Speed and Tama, he just roughed them up.
With pirates like Luffy/samurai like the Scabbards, Kaido WANTS them to survive so they can COME BACK LATER AND KILL HIM. The only reason Kaido lets them live IS BECAUSE HE WANTS THEM TO GET STRONGER SO THEY CAN KILL HIM. And we still haven't gotten his full backstory from King, ugh, I love Kaido.
Mihawk/Shanks/Black Beard are impossible to scale right now, IMO.
But, as far as we've seen, Kaido is BY FAR the strongest character in this series. Big Mom took relatively no damage until she fought Law and Kid directly, and still lost before Kaido did, despite Kaido:
-Getting surprise shanked by the Scabbards
-Taking all of the Scabbards best attacks (as in willingly letting them attack him)
-Taking multiple powerful attacks from Law, Zoro, Kid, and Killer
-Fighting Luffy until Luffy was knocked out twice
-Fighting Yamato for a brief period as well
Kaido is the strongest character based on feats BY FAR, it's not even close right now, people who thought Kaido didn't do enough are just insane. People act like Kaido is weak because he doesn't kill often, but Kaido is only willing to kill if he deems it necessary. Even with Speed and Tama, he just roughed them up.
With pirates like Luffy/samurai like the Scabbards, Kaido WANTS them to survive so they can COME BACK LATER AND KILL HIM. The only reason Kaido lets them live IS BECAUSE HE WANTS THEM TO GET STRONGER SO THEY CAN KILL HIM. And we still haven't gotten his full backstory from King, ugh, I love Kaido.
Mihawk/Shanks/Black Beard are impossible to scale right now, IMO.