Hercule. Not only is he fucking hilarious but without him the fights against Cell and Buu would have been lost.
In the Cell games he showed incredible bravery to throw 16’s head over to Gohan, enabling Gohan to hear the words he needed to go super sayin 2.
In the Buu saga, he befriended a monster, he showed kindness and compassion that was nearly able to end the fight before it even started. This later caused the good and evil buu’s to split. Without Hercule, Goku would not have been able to power up the spirit bomb that finishes Kid Buu.
One of my favourite things about super was to see the original Goku character come back. A goofy and loveable guy that’s a savant when it comes to fighting and just wants a bigger challenge.