We have a Gravity Hill and it earns well. The problem though is we've had it for about 3 years now, and some of the local kids have completely mastered it. They'll repeatedly win the big prize until they get bored.
Redemption is our top earner, even the lowest earning redemption games still bring in more than most of the video games.
Rhythm games (like DDR) are second place, especially the games we have imported from Japan. There is a very niche audience for these.
90s driving games and the big deluxe simulators (Top Skater, Alpine Racer, etc) come in third place.
Shooters and fighters are fourth.
Classic games are last, with the exception of Pac-Man, Donkey Kong, and VS. Super Mario, those still do pretty well.