I would have picked goku if i wasnt spoiled so hard about his transformation before it aired. By the time he did it, I already knew when, where, and how he was going to do it due to spoilers from word of mouth and watching specials (with him already transformed) elsewhere in Japanese.
The western audience had to wait forever iirc. I had little intel on gohan's transformation.. hell, i even knew about trunks and his transformation from a vhs promo video that came out YEARS before trunks' actual transformation. Hilarious.
It was this: