I've had about 1/2 the SS Bally's at one time or another.
Some heavy regret sells in that herd too.
The $850 Frontier I passed on 10 years ago remains my worst pinball decision ever.
Right now.
Fireball2, Eight Ball DeluxeLE, Xenon (here on loan), Fireball Classic, 6Mill$Man, Eight Ball Champ, and Paragon - and they're all staying!
They are the classiest looking games, they are always challenging, and the art is made for adults.
2 remain that I've never seen or played, Voltan and Gold Ball.