Bill Zebub
“It’s probably Matt Mercer’s fault.”
So far the one my group is playtesting seems to be turning out to be one of our favorites (GEAS).
No spell memorization or prep. If you know it, you know it. Every spell requires a roll. While no mishap table, if you roll all 1s (it's a dice pool system), it's a spell disaster. So far that's super rare (especially as you gain in power, your die in your dice pool go from d6s to d8s to d10s, etc.). Additional successes lead to greater spell effects. That's not the only way to make spells more powerful, as you can invest vigor (stamina pool) to boost your spells if you want. So a caster can really pump up a spell if they are willing to exhaust themselves doing it.
In addition to the above, the rune magic system is a list of runes that you combine into spell effects for a final spell. That really seems to be going over well for those players who like complexity and thinking outside of the box for creative solutions. An example includes combining a rune trap rune with a gust rune with a burst rune to send out the spell to a distance where it lays until triggered, then explodes. Basically an MLRS system in fantasy PC format lol.
I like the idea of a dice pool for casting. That nicely evokes the complexity/variability of how I think magic should work.