Luffy's anger for Charloss shooting a friend of his vs Kuma's rage for Saturn sabotaging his whole life and trying to sabotage his daughter's for years.
Luffy nonchanantly walked up to punch Charloss, who at the end of the day is a pathetic weakling. Kuma saved his daughter, serving as a shield as he did his whole life, and punched Saturn right in the face while he was in his Awakened form (Kuma wasn't even supposed to be sentient and alive at this point, Saturn triggered his self-destruction switch).
Oda's style became clearly dirtier during the years, so Luffy's hit is more clean without a doubt, but Kuma's panel properly conveys the pure rage of a man who lived his entire life suffering because of the system his enemy rapresents and enforces.
Again, Kuma's is more brutal.
Again, Kuma's comes from a totally different level of retribution. Luffy was doing a noble act but Hacchi was his friend from, like, a day (?).
Kuma wins on all fronts.
You can say Luffy if you feel nostalgic tho.