Definitely Freeza. The Turles fight was even for a bit, then Turles ate that initial fruit and stomped on Goku... literally. Then when Turles' guard was down, Goku used Earth power ex Machina to kill him.
To sum up the Freeza fight (because putting the whole thing to text would take way too long) Freeza and Goku beat each other up, Goku blew up Freeza with the spirit bomb, which didn't actually kill him. Freeza kills Krillin, unleashing the beast within Goku, and gets beat up. Freeza goes 100% and they're about even again for a while. Then Goku gets bored, tries to leave after telling Freeza that there's no way that he can win, then Freeza tries to blindside Goku. Finally Goku actually slaps Freeza like a bitch, Freeza gets halved by his own attack, and Goku blows him up a second time.