If done well, I don't think I have a strong preference for reading one over the other, but I find a lot of Fantasy really doesn't... get creative with the whole fantasy part of it. Like, woo, it's Lord of the Rings + DnD and dragons are the good guys. I haven't seen this one before, nope. I think sci-fi inherently gets more creative because there's more "genre-defining" works of the same caliber - and they kind of end up fostering creativity because of how much they clash with one another.
For writing I basically always choose sci-fi, even if it's the Clarke's 3rd Law kind of sci-fi (sufficiently advanced technology is indistinguishable from magic). Actually, I absolutely LOVE stories that have characters exploring the world-building aspects of the story and trying to understand it (i.e., the scientific mindset).