Star Trek for me. While I was and am a huge Tolkien fan, I'm generally more of a science fiction fan more than a science fantasy fan. Star Wars is the latter. Not to mention, with the exception of Rogue One, I haven't seen a good Star Wars movie since 1983.
Hated the prequels, with the exception of Revenge of the Sith, which was as close to science fiction as the entire saga got (social and political allegory).
The last trilogy was nostalgic tripe on the level of the last Jurassic Park trilogy.
Meanwhile, FOR ME, the science and social, political, mortality analogy is more science fiction, by definition. Definitions aside, it just keeps me more engaged.
There's nothing intrinsically wrong with science fantasy (or any fantasy, for that matter). But generally speaking, it doesn't keep me as engaged.
This was a great question! Even if you're now sorry you asked it.
Next question: seashore or mountains?