Honestly, I just really like D&Ds (and more specifically Pathfinder's version) Vancian style spells and slots (and rituals). It just works and feels good.

Fail at casting a spell? It's just nothing. No warp silliness, no blood cost, no problems, just a fizzling nothing.
Want to cast all day? You're stuck with the weakest spells possible, little blasts of elemental power or little more than tricks.
Want big magic? Rituals! The community blessing crops every year to increase growth and counter blight? A giant Plant Growth ritual.

Its works really well to give the world magic, and you can throw little nuggets of fun at players without needing to worry about unintended effects from overcomplicated rules.

People always want to overcomplicate it, write lots of rules and weird lore for magic but at the end of the day most of them are shit, overcomplicated nonsense, and often turn out more fun to read than to actually play (and arent all that fun to read in the first place).