When I was into Ars Magica it was still a Lion Rampant game. Much newer, fresher, and un-baggaged.
I could never get into Unknown Armies. It ranked up there with On The Edge and Nobilis as games too in love with their own wierdness. For me they fit into that bizarre 90s era RPG state of repressed authors who’ve developed a high volume of setting material but can’t come up with a compelling plot…so instead of writing a novel they dump the setting into an RPG and punt the plot to players…and only tack on some rules as an after thought. Drives me batty.