Lewis/Rahman II sounded like a shotgun going off! Even the first punch, which didn't look like it had much weight behind it was incredibly loud. Martinez/Williams II was another. Your choices are?
When David Lemiuex is really on, his punches make an unreal sound when they land. The ringside microphones really pick them up.
Years ago I was ringside for a small card in Pennsylvania. Bert Cooper was in the main event and I'll never forgot the immense thud his shots made when he was going to the body.
Seeing Inoue in person (vs. the Puerto Rican guy on the Rungvisai-Gonzalez re-match card) I felt his punches had more of a sound than just about any fighter I can remember.
My friend said that the shots that Tyson was landing on Julius Francis could be heard around the arena. Literally like a shotgun going off.