Well? For me it would have to be Double Dragon. Man, in 1987 that shit ran the arcade. Always would be a crowd. Always a 20-30 minute wait time to play it. I got so good at it though I actually made it to the last boss with one quarter an no partner. Of course it cost me another dollar at least to take down the machine gun final boss but I had all the strategy. Knew exactly where to stand so when I dropped my weapon after I beat a stage I could pick it up again on the next stage, timing was perfect with the bat so I could loop dudes into a hit cycle when they tried to get up until they died, threw every dude into any kind of pit there was around everytime, etc. That game was it for me.