I like the Sov Stone system because, while it makes magic more natural and flowing, it also maintains the old archetype of the great wizard pouring over tomes of forgotten lore. That is something you lose completely with things like Mongoose's Chaos Magic, for example. There's no longer any need to search for ancient, forgotten, secrets and lock yourself in your tower studying forbidden tomes to fuel your power.
Sov Stone has a perfect blend here because you can cast some spells without a book because you know them so well, while others still require a book because you aren't as familiar with them. You also still learn spells from written form.
I also prefer the idea of discrete spells to creating effects on the fly when you cast, since again it encourages the feel of gathering a body of hermetic knowledge. If magic is too freeform, then it loses the sense of archaic ponderance that makes magic seem so occult and mysterious to me.
Again, Sovereign Stone has a great blend here because it uses discrete spells but then provides a system for DMs and players to build these spells in a freeform manner behind the scenes. The character in-game has to do research to invent the spell thus created.
In both cases I get the best of both worlds with Sov Stone in terms of what i'm looking for. Does Elements of Magic support book learning occult lore, research into the forbidden arts, and spell books? Does it support discrete spells or do you create spells on the fly, inventing effects when you cast?