This has always been tough for me because while I think I have a general preference for sci-fi at least on an aesthetic level, often my favorite aspects are things in various sci-fi settings I like are the parts that either could be or just outright are closer to fantasy than sci-fi, like The Force in Star Wars, or the variety of alien species in general. I'm definitely the biggest fan of when they intersect, which is probably from my very early exposure to FF8 and Breath of Fire III, but I also just think that it maximizes the potential for a setting to have both present. That's not to say that I think every setting needs both either. I think outright magic and dragons and such would feel just as out of place in something like Megaman as a spaceship would feel in Lord of the Rings. When a setting is made with both in mind though, like the Eberron setting for D&D, I think it usually ends up being really solid. Bonus points if magic is treated as a science or an aspect of science, since it's often treated that way in regular fantasy anyway.