I'm a fan of the side scrolling brawlers like Final Fight and Double Dragon, and also the vertical shooters like 1941, 1942, 1943, and especially GUNSMOKE!
I think I'm building a cabinet mostly just to play Gunsmoke. Maybe on some subconscious level I feel it might make up for the hundreds of dollars I pumped into it back in High School. Whatever the case, Gunsmoke will always be my number one played game!