Um.. Piccolo?
*Engar runs from screaming mob*
"Wait! I have a reason!"
Piccolo isn't the power house of strength that other members of DBZ are, he copes in the later part of the series through sheer willpower and skill. He isn't full of pride like other fighters, has had to deal with a hatred for Goku which he was born to and, for the planet, did the unthinkable and fused with Kami.
Piccolo went from being evil, caring only for himself and
wanting to take over the world to being someone willing to sacrifice himself for the child of his greatest rival. He might not have been part of the greatest anime, but he had all the qualities of greatest anime character.
Determined, coped with terrible childhood, willing to die (more than once) and.. so on.. o_O
....
And he's really cool!
(There, I had good reasons and I didn't pick someone who looked great (for that, go Washu) so please don't hurt me..)