I've enjoyed high-fantasy magic, but the idea of highly scientific magic is also very fun. On one hand, sometimes you just want to see a character throw a fireball. On the other hand, sometimes you like there being a logic and method to what is basically a world with extra laws of physics. Magic in the stories I create follow one main principle: they are sourced from the universe itself. What this entails differs between settings, but magic is always explained as having an identifiable source. That source may not be identified by the characters within the universe, but they should have a source that can be explained to the reader.
For example, magic in UBHG is the act of manipulating the environment. It had the most "scientific" magic system out of all of my settings. In it, magic exists within what we broadly think of as "the laws of physics". Fire magic is the ignition of combustable materials by raising the temperature of said materials. Ice magic is the freezing of water by lowering the temperature of the water. Gravity magic is an in-universe misnomer and refers to manipulation of magnetism. So on and so forth, each "type" of magic comes from humans being able to manipulate specific things. With that being said, I have no explanation as to how people can quickly raise the temperature of the air at their fingertip and ignite dead grass to light a cigarette.