I'd have to say magic. It feels like it's much more capable and doesn't have as many rules. With technology, there has to be a certain way you're supposed to use it and most of it's probably really expensive so you have to take care of it and make sure it isn't damaged. Magic you just have with you whenever you need it, you can get creative with it, and for the most part, it's expendable.
Why not both? Recently been introduced to Shadowrun by a lovely bean on this very site, and it manages to splice fantasy and sci-fi rather well.
However, if I HAD to choose ONE, I'd probably go with magic - Can do everything futuristic tech can do, except less maintenance and chance of your stuff being hacked and shocking you to death.
Final Fantasy XV - Magic and Tech is such a beautiful baby. But if I did have to choose, I would go with sci-fi, I can comfort myself more with science and its laws. That and I may have a guilty pleasure for mechas and space battle.
I like to have my cake and eat it too. As Mr. Clarke teaches us with his third law: Any sufficiently advanced technology is indistinguishable from magic.
Sci-Fi and Fantasy are my favorite genres and depending on the plot and thematic elements involved, it takes but a small bit of outside the box thinking to write magic that functions as technology and vice-versa; if you need a particular effect, both can provide it.
In a lot of media, futuristic tech is really just magic with a sci-fi skin tacked on. Usually, I'd refer to that as science fantasy. And although science fantasy is cool too, I really prefer some good, well thought out science fiction. That is, fantastical elements of futuristic technology supported by some kind of justification that at least tries to sound science-y haha
In general I prefer magic. Rather than pretending to understand concepts that they quite simply do not, the creator(s) just work with a system that they themselves create.
However, I still do love some sci-fi. Mecha are cool, nonsense laser weapons and teleporters are cool. But generally sci-fi I do like is just magic with a "scientific" explanation that clearly does not hold.
You know honestly, I cant make up my mind. I use to think magic is so exotic and cool (as a kid and teen), but advanced tech has its charm too. I think a combination of the two wuld be the best. Magi-tech or something!
I'd go for tech at a first glance, because it's grounded in rules that impose limitations, making its creation and use feel more of an achievement. However, magic has its appeal, especially when it's unpredictable or unknown, adding a quality of adrenaline to its use that sci-fi tech can't reach without breaking its own laws. So overall, tech if it has opportunities for advancement and alterations, and magic if it is alien in some form.