My top five are:
1. the Dungeons and Dragons that was out about ten years ago: that one allowed up to four players if I remember correctly and my brother and I used to play it all the time at Geneva-On_The_Lake.
2. the coin one where it pushes the coins down and gives you tickets: a friend of mine and I used to have competitions to see who could get more tickets that way
3. Darkstalkers: one of the few fighting games I played because of the cool characters
4. Air Hockey: a friend of mine and I got warned at one arcade about that game. He used to hit the puck so hard it'd go flying off the table, not because he was a bad person. He just sucked at the game sooo bad.
5. those crane games: one year a friend of mine and I got so good at it, we nearly cleared out the machine every time we went (the jewelry one was the one we played)