I’d say both. Sci fi means there are elements that the story pretends could be possible, which includes time travel (probably not the tardis, but most other methods), space travel, and most alien races probably including one’s like the daleks and cybermen. Fantasy means there are things that the story fully admits are not possible in our world, which covers time lord regeneration.
There’s plenty of other things that are both sci fi and fantasy: star wars, warhammer 40k, and marvel or dc superheroes.
I’d say both. Sci fi means there are elements that the story pretends could be possible, which includes time travel (probably not the tardis, but most other methods), space travel, and most alien races probably including one’s like the daleks and cybermen. Fantasy means there are things that the story fully admits are not possible in our world, which covers time lord regeneration.
There’s plenty of other things that are both sci fi and fantasy: star wars, warhammer 40k, and marvel or dc superheroes.