The kiss. Both the kisses. And "Never doubted him, never will". Jack/Rose/Doctor is right up with Don/Kathy/Cosmo in my OT3s.
And firing his gun to get the people's attention on Level 0, and that speech, oh my God.
And facing the Daleks coming to kill him, shooting until he ran out of bullets and then just standing to take it and oh my God I actually screamed when he died, even though I knew he was coming back somehow from the casting spoilers.
And he's alive. They left him there, but he's alive, and they'll go back to pick him up.