Even if the final fight with Diavolo wasn't that good at least he went out with one of the most brutal ends for a villain in fiction history and it was built up throughout Part 5.
DIO's death was pretty similiar but it was just a really strong punch and he was powered up already.
Also add that it came out of nowhere.

By the way:La Squadra di Esecuzione > DIO's henchmen. They were much fewer but they felt like a much bigger threat.

The Execution Squad was trained specifically to kill and, while they hated their sitting position in Passione, they can do their jobs efficiently, they just had the misfortune of fighting a newbie who happens to have a busted stand. DIO's Henchmen were just sadistic dicks who couldn't care for DIO if it wasn't for the money he promised them. There's a reason why, outside of Vanilla Ice and Pucci, they didn't do much to the group.