It's not an insult to Chuck, who had a similar KO rate against some similar opposition, but never faced and KO'd a HW champ.
It's not an insult to Rumble. Actually I'd think Rumble in comparable as a KO artist, but Conor is clearly a superior striker.
Silva is one of the very, very best. I think he's #1. Diverse, precise, powerful and above all, super consistent. And he did it at MW and LHW which is extra impressive. He's only faded because let's face it, in MMA terms he's ancient. There's no shame in declining at his age - it's remarkable he was so effective for so long.
It's not an insult to JDS. A ridiculously powerful HW? No way! JDS is a decent boxer, powerful and durable. But he isn't better than Conor as a steiker overall.
It's definitely not an insult to Edson, who has beautiful kicking technique and improving boxing, but not always the nous to capitalise and lacks finishing wins against high level competition. He does have the prettiest spinning kick KO ever though. Amazing stuff.
It's not an insult to Belfort - much as I like him - who needed to be marinated in concentrated T to get the best results. Belfort has fast hands and an amazing blitz, plus some really nice top wins. But not much consistency and a love of 'supplements from heaven'.
It's definitely not an insult to Arlovski, who had some one the nicest boxing at HW (I think Stipe is better) and a good finish rate, but lost plenty.
Cro Cop is an interesting one. A great striker, but not always so in MMA. In the UFC particularly he was quite tentative and didn't look like a killer at all, and was finished by some pretty ordinary strikers. A great KO artist and certainly looks good if you count his PRIDE career as well, but across his career as a whole, not consistent. Conor better overall, beating better competition and stopping them consistently.