Although I like free form systems, my players tend to be more comfortable with lists. You have to find new spells and reagents through adventuring, which is perfect.
But...
It would be really nice if a lists based system is actually based in something like Mage's spheres of influence. That makes it much easier to say what sort of spells can reasonably be found in the lists coming out of different disciplines, cultures, etc. It also provides "styling" when two disciplines can achieve the same effect but use very different sources of power. Finally it's great for research game play, or NPC researchers.