To my limited knowledge on the subject QSAA, is shorthand for Nvidia quincunx super aa, using a 5 point method for aa yields about 2:3 performance gain in processing overhead to MSAA, or standard AA. So a 2x QSAA does what 3x MSAA does(ish), at the 2x MSAA computational cost. Better or worse would be pretty subjective and game dependent, I happen to like aa more than I like jaggies... on some games with some motion blur built in, maybe not so much. Something like Civ 5, which has 8x QSAA, it looks really nice and is quite smooth zooming in and out... but there ya go.
So back to the OP 16x QSAA ~ 24x MSAA Level, utilizing 16x MSAA Processing/comperable GPU cost. Though, nothing for free, could make the scene a touch blurry if there is some built in motion blur in the scene.