I don't get how people think Abom and Hulk can beat him down. Fodder plus fodder equals fodder. If you can't hurt somebody with a punch, throwing someone else who can't hurt him in will not change anything, they can't hurt him either. Thanos stomps.
Thanos wins, and it's not a close fight. Prime thor as confirmed by the Russos is hundreds of times more durable than average asgardians, and he was essentially wrecked from no more than 10 hits from Thanos. He one shots until they all are gone. Piercing weapons is what he has to worry about, but his armor should help him with that.
Voldemort still wins. Movies may have dumbed down his power, but book one is stated by Albus himself to be the most dangerous dark wizard of all time, and confirmed by J.K. Rowling herself as the most powerful dark wizard to ever live.