(Aside: why is it that most cocktail-cabinet arcade game machines around these days are Galaga? Is it the result of some kind of technical and/or memetic survival-of-the-fittest?)
As far as the shooting-flying-things genre goes, I preferred Gyruss. The polar coordinates were a nifty gimmick, and the rendition of Bach's Toccata and Fugue added to the atmosphere.
Gotta d/l link? :-)
Because it's a great game, iconic... and very very widely bootlegged. As a result, it runs on a bunch of different 80s-era arcade platforms.