Goku. The inspiration, minus a brain and plus an inconvenient tail.
Krillin, Yamcha, and Launch were cool. I liked Puar and Oolong together. The other characters interacting and doing their own thing makes the series what it is.
I think Roshi takes it for me. Absolute badassery during the 21st and 22nd Budokais.. seeing him get serious when Piccolo Daimao was released.. It was nice to see that he wasn’t just a gag character and actually played a role in the story.
Kuririn. Ever since his introduction, he was the most interesting member of the main cast due to having a notable character flaw in his lack of confidence and seeing how his experiences would either help or hinder his development of overcoming this was always interesting. The other cast members did have character flaws, but they were either ones they quickly discarded after the first arc (eg. Yamcha's fear of women) or ended up just becoming a gag trait (eg. Roshi's perverted nature).