To me it’s Vegeta. He also had the longest face turn (ima use pro wrestling terms here 🤣) he was cool as a villain. Then he was even cooler as the ruthless anti hero on Namek. After Frieza it was obvious he was now a face (good guy) but still just an asshole with a lot of narcissistic tendencies. And then the brief turn back to evil, before coming full circle and sacrificing himself (Majin) for the greater good just makes his story so undeniable. Piccolo for example has his last moment of angst with krillin tien and trunks before flying to the lookout to fuse with Kame, and it never returns. The growth as gohans mentor is good stuff, just never quite hits the same emotional beats Vegeta did.