If I had to pick it would be future Gohan. If you don't know, in Trunks's timeline, Goku died of a heart attack. And when the androids appeared,  they were merciless killing machines. They killed all the Z-fighters and nearly the entire human population.  The only person who could stand up to them was Gohan, as he grew up training over the years. He eventually took trunks on as a student,  teaching him to defend himself,  and to become a super Saiyan. Since Trunks lost his father and the others, he didn't have that push to become one. But one day, Trunks and Gohan fought the androids,  and in the process of defending Trunks from a deadly blast, he lost his left arm. Months past, and Trunks is slowly getting better than he was back then. But as he and Gohan were talking, another town was being destroyed.  Gohan was about to take off when Trunks wanted to go to help. Gohan apologized and knocked him out. After a long battle, Gohan was overwhelmed by 17 and 18, dying in the battle.... if it weren't for him dying, Trunks never would have went back into the timeline to save Goku... he's the most badass character around in my book

Gohan: You know you can't win! You can't destroy what I really am! Even if you manage to kill this body, someone even stronger would surface and take my place! Not one death will go unaccounted for. Not one!