Generally I lean towards fantasy, but I do hold a deep love of sci-fi also. Two of my larger influences growing up were Halo and Fable, so like. yeah they're both dear to me. However! I would be remiss to not bring up my favorite shit, which is when you blur the lines between one and the other.
I had a concept for a d&d character I never got to play who was a warforged druid. Their whole deal was that they were, in fact, a suit of artificer-style power armor whose pilot had died inside of, leaving themselves to be overtaken by nature, until eventually, my character woke up, an almost empty suit of armor tangled in vines, save for the skeleton still rattling inside. Similarly, one incredibly sick thing that Diablo 4 did was make a certain faction of enemies have a unit that was A MECH BUILT AROUND AN IRON MAIDEN. THEY WOULD STICK A SOLDIER INSIDE TO SACRIFICE THEMSELF AND POWER THE MECH BY THEIR FAITH. THAT'S SO FUCKING RAD.
Alternatively, as hand-wavey as it can be, I deeply enjoy psionics in sci-fi media as just. Yeah some people's brains are fucked up in a way that lets them do magic. Go nuts. The Protoss. An entire race of psionics who, as far as i can tell by their lack of mouths, subsist off psionic energies from their environment. Rad. Also like, as much as I feel that Destiny has suffered lately [multiple years now], paracausal bullshit powers is fucking tight!
So it's hard to say which I prefer more, partially because I really like to blend them up. Colt is like that. In her present lore, she's living in a magi-industrial revolution time period, where people have learned how to engineer guns that fire spells instead of bullets. She lives out on a hyper-dangerous frontier that is subject to extreme levels of latent magic that lets her basically treat said magic guns as if they were on an overheat-style system like Halo's plasma weapons, unlike everywhere else in the world where you gotta replace the cylinders to reload, because the little batteries of mana that power the guns are built into the cylinders themself. far too costly to produce to be ejecting like typical bullet casings, y'know? but again, where she lives, those batteries absorb enough background mana to recharge in seconds. Anyways yes. To answer your question, uh. Both.