I used to clean up on the coin-drop games with the moving slide thing. It takes a few coins to get a rhythm down, but it's worth it.
That one, Operation, Skeeball, and some coin drop/spinning wheel thing are my big winners. Especially Operation, I can score 30-40 tickets per coin the majority of the time. Plus, the mini-person really likes feeding tickets into the ticket muncher.

I think she has more fun with that than a lot of the games she likes playing.
Oh, and she thinks I "Win" her the ice cream out of the vending machine... I'm sticking with that interpretation