A lot of people like me like Futa/Female because it's clean, when it's Futa/futa there are just too many dicks swinging around, although some can be good if its done with a high quality. The key point is that Futa/Fem enjoyers still love non-futa women, typically they have the mindset that female > futa > male in their attraction scalings, if that breaks it down enough for you.
It's not that I don't like futa/futa though, I just prefer futa/fem. My preferences would be futa/fem > fem/fem > futa/futa > male/fem.