Haven't played demon souls. Didn't love elden ring. Of the remaining DS3 is my favorite but part of that i think is just because it's the most familiar. Sekiro and bloodborne i loved as well. If i had to choose i think bloodborne 2 because id love to see more of that story the most alongside new atrocities, and i really loved the layers of exploration/shortcut it brought.
I'm curious, when you say sekiro has so much untapped potential, does anything in particular come to mind?