They achieve different goals for me but both are great to consume in porn.
For the landlady route, I think my favorite is how My New Family did it. But also, I do like how Monkey Business did it too. I can't choose between the two.
For the roommate route, I love how the MC and RM have always had that kind of relationship. There's a lot of games like that but it's way better for me when their relationship is constant from childhood.
I feel like you can get a similar feeling for incest with mother with an older aunt, cousin, or just the MILF category sometimes. Hell, sometimes when a woman refers to herself as "Mommy".
But incest with the sister? It just feels one of a kind
i usually prefer sister, but when its a hot milf with a loving personality, there is something special to her slowly seeing her son as a man, then as her man ;p