Sci-Fi is harder to produce successfully than Fantasy, unless you are writing Dystopia. Dystopia seems to go as easily as Fantasy, particularly if it is something about The Only One Talented Girl.
Sci-Fi has harder to imagine worlds, as you do not have cultural benchmarks, and descriptions of landscapes and aliens take mastery – unless you are drawing. You also have a baggage of terms you bring in as you build SciFi world, vs fantasy that can used a lot of familiar ideas, such as LoTR and HP species.
In Sci-Fi, the biggest verses are (still) Star Wars and Star Treck (unless you count super-heroes verses) and Star-wars like Sci-Fi attracted female viewers more than ST – viewers, mind you, how many had read the books in either verse?
Sure, you can focus on the human issues, and avoid a lot of that, but you are also letting go of a lot of popular tropes that feed fantasy. Oppressed females, with the Only Girl That Could for an easy canned version of a ‘strong female main’ & the Abusive Powerful Men are less justifiable in Sci-fi (or at least one would hope so!)…
All and all, Sci-Fi closest to the SW (and dystopia) will have better chances on WP.
That said, anything is hard on WP now, even the badboy billionaires.