Stans is excellent for sealing tire beads on tubeless tires, and only so-so at sealing punctures in tubes, and ineffective against pinch flats. The fluid is a liquid latex that needs to air cure so results aren't instantaneous (a pump is still required) and its life expectance on a tire is only given as about seven months by Stans -after which it needs to be renewed. A mtb tire typically needs 4oz and a road tire 2oz.

Flat Attack has a life expectancy of five years, is useless at sealing tire beads in tubeless tires and very effective at sealing punctures in tubes. Its also fairly ineffective at dealing with pinch flats. The problem is that gravity and centrifugal forces pull liquids away from where pinch flats occur - around the inside of the rim.

Pick your poison.