I think Shanks and Roger might be stronger in multiple ways:
1. Their FS vision is more than twice as long (10s)
2. There are prolly approximately 4-5 sub tiers of CoC strength around the top tier lvl: WCI Luffy < Ryou Luffy < Skysplitting (solid top tier) < drunk Kaido =< PK tier
And they are at PK, whereas Gaban is prolly at skysplit
3. WIFI haki as an established tech: they might have blasted away the thorns on the ground with a CoC blast on the basis of will suppression or some
4. They are "hybrid" fighters:
- raw blade with haki = high lethality
- advCoC blast channeled through blade = max AP/impact power + internal damage and not just recoil (contrary to otherwise normal barrier haki)
5. Gryphon shenanigans
Ray likely has a more efficient/better fighting style with more refined techs similar to traditional swordsman, basially Killer compared to Zoro, prolly stronger CoC and some sword shenanigans that played into the dark king epithet