Another that I liked a lot which not many others did was Xevious.
I had a friend who spent a helluva lot more time than anyone I knew at the Machine Shop arcade in South Hills Village and he mastered MachIII. Spent HUNDREDS of dollars doing it...
My son just beat me at Galaga and set the hight score on our machine. He's 8 and enjoys playing the classics on this system. I was on a Berzerk kick one summer. It makes me feel pretty good, now that I own the machine, when I hear that "Coin detected in pocket!" "Kill the humanoid".
My son kicks my you know what on all of the Street Fighter type games on this thing. I just send him to his room. :-)