Easily the Chuck KO. Validated his place as one of the LHW GOATs for the Shogun fans that knew him, and became fans during his PRIDE run, and shut up the ZUFFA/PRIDE haters for a second.
I remember the remedial fans that just got into MMA from the Forrest/Bonnar TUF match, calling Shogun a bum, because he lost to Forrest, coming off of major knee surgery, and not knowing that a pre injury Shogun would've smacked Forrest all around the cage, and the true PRIDE Shogun was never truly coming back, but we had glimpses with the Chuck, and Machida fights.
He's never looked as great as he was during his 05' run in PRIDE, ever since the 2nd knee surgery. He was so great, he got the UFC gold, without knees.