They're both the same. Total sociopaths who sadistically manipulated an innocent person's heart for their selfish ambition while planning on killing their victim's sibling (blood or adopted) out of hatred, and you don't see the plot twist coming until it's too late. Also, both reveals happened in 2013.
However, when it comes to quality writing, Hans wins out because he actually thought ahead of his plans and took any advantage that came to him, and only failed because Olaf came to Anna's aid after he smashed her heart. Oddly, he was never meant to be the villain of Frozen; the original script had Elsa as the villain, and Hans as a supporting character.
Penelope was the victim of bad writing from a different developer who wanted a cheap plot twist and decided to make her as amoral as possible to deny Bentley (Anna's counterpart) his happy ending in the cruelest way possible. In the third game, she was genuinely good and had a crush on Sly (Elsa's counterpart) and saved Murray (Olaf's counterpart) from being blown up in the fourth chapter. In the (wildly considered non-canon) fourth game, she's trying to murder them both out of spite with the motivation being "they're holding Bentley back from making me a profit in the billions".
While both have "lust for power" as one of their motivations, Hans only wanted to steal Arendelle's throne because he was 13th in line for his own kingdom's, and he had a poor relationship with his family (in contrast to Elsa and Anna). Penelope's main motivation is greed, and she states that she'll "change the world" with any weapons (yeah, WEAPONS) Bentley builds. This could mean she aims for world domination through death and destruction, showing her contempt for life in general in favor of the money she could make with such weapons. At least Hans treated Arendelle's subjects with kindness and gave away food and blankets after Elsa accidently unleashed the Eternal Winter.
Penelope comes as the eviler of the two... unless you take Kingdom Hearts III (2019) into account, where Hans turns into a Heartless called Sköll and decides to destroy everything out of anger for not becoming King of Arendelle. Then they're both just as bad.
