I liked magic in Shadowrun, actually. At least the old editions, I dunno how it is now. Speaking of Shadowun 2nd edition, which is the one I played the most, you could cast any of your spells as often as you wished, and you could choose each time how powerful the spell would be, but then you had to resist Drain, which would fatigue your character (or even knock them unconscious, or in rare cases kill them if you tried to do too much). If you were careful and judicious with the power level of your spells, you could effectively cast forever, but if you tried to push it then you could mess yourself up. It was a lot of fun to play a mage in that game.
