If anything Perseus was just saving people and didn’t sacrifice anyone else's life in the process, Perseus only killed the wicked or people that have done wrong, when Odysseus killed a bunch of innocent people just for trying to wed his wife when they thought he was dead. Perseus may not have saved everyone that was attacked by the sea serpent, but he was the the one who slayed the sea serpent and saved all the other people from the beast of the sea and kept them safe and even god a bride for him to marry from the town.
Finally Perseus never put anyone else's life on the line to achieve something, he always saved people if they needed saving, while Odysseus got all of his men killed, not on accident but he wasn’t powerful enough to save them all. The only real bad thing Perseus ever did was accidentally kill his grandfather at a disc throwing competition. Perseus killed medusa without sacrificing anyone else’s life to do so, he also had assistance from the gods to achieve his goal and kill the terrible king.
In all fairness some people may say that odysseus was a better hero because of how many challenges he overcame, but every challenge he overcame he sacrificed one of his men to achieve. Also