It was in a guide/book called Dragon Ball Forever that came out in 2004. There were only two Shonen Jump polls for Dragon Ball, one for the Cell Saga and one for the Buu Saga that only had the top five. In those, Gohan beat Goku as the number one character for the Cell Saga, but dropped out of the top five in the Buu Saga. Gotenks was number 4 in the Buu Saga poll.
Most online polls tend to be western linear. For example, Vegeta beats Goku in many online polls, while Goku trumps Vegeta by a country mile in the Japanese polls. Or like Cell who is ranked as one of the best villains in online polls is only a 14 in the Dragon Ball Forever poll.