"Which do you choose, a hard or soft option..."
Magic systems in fantasy! They are not all alike, as you know, but here's one of the ways to categorize them: a spectrum between "soft" and "hard" magic. Hard magic systems have defined rules on how they work, and the reader is told what they are—e.g., the four element types of bending in Avatar: the Last Airbender have certain basic limits, which is why the characters are astounded when, say, Toph invents metalbending. Soft magic is more mystical and indefinable—e.g., we don't really know HOW Gandalf does all the magic he does, or even what his limits might be; we just accept that he's a wizard and such things are unknowable to the likes of us.
I tend toward soft magic, though moderately so, in my fantasy books, because I feel like the more you give precise, quasi-scientific explanations for magic, the more it's likely to bug people who actually know science. (Also the closer it comes to being science fiction instead of fantasy.) That said, I do put limits and costs in my magic systems: the fae in The Goblins of Bellwater (and Lava Red Feather Blue), though very soft-magic in terms of having large and undefined amounts of power, must nevertheless adhere to deals they make, because that's just the rule.
I also tend toward preferring soft magic in reading, because I don't REALLY feel I need pages of detailed explanation about which material and which rule loophole and which move is the way to solve things; I'm good with a briefer and more mystical explanation. However, many readers do love the details. Neither side is wrong! It's a matter of preference—and it's also on the shoulders of us writers to be consistent within a given story, whatever slot on the spectrum we're picking.