Imo it's Clea, Penelope get all bad endings but as she cleverly listen and stay low without any help, she's still alive(for now...) while Clea's lucky that there's gossip maids that made it easier for her to persuade him in a proposal. Plus every step you take is one step to death's door and the pain and blood that comes with it.
All in all they were in one of the worst situation every isekai stories out there
I admire Penelope very much for enduring such a cruel abusive system that restricted her movements.
Remember when the system give her only very few options to choose and forced her to eat that polluted soup? That was very hard to watch... She also has to deal with the favirbility meter with all these shitass MLs...
Clea is more light hearted and funny. Liked that she is very angry at her murderer. Despite always watching her declining HP, she still make the best of it. She had a choice (take the deal with the demon or die) and has more freedom to act.
They both should have been girlfriends or soul sisters.

Penelope Eckart from Death Is The Only Ending For The Villainess or her Clea?