That is indeed a very difficult one. As far as power goes i would have to go with Goten and Trunks, which has to do with their fight with 18. Now yes when fighting everyone was restricted, 18 not sure how strong they were while dressed as the mysterious fighter, and Goten and Trunks having restriction where only one could punch and see, and the other kicks. In the end it pains me to personally say it since Future Gohan is one of my all time favorite characters, tied for number 1 with Goku. But Goten and Trunks do take this. BUT!!! I say this without really doing much research and not having watched the series in awhile. So my answer might change, but at the time the victor is Goten and Trunks, TAKE A BOW!