Going by your Pinside avatar I would say Bally Star Trek is the game you need to complete your line up.

I would also put Fathom on the top of my list for classic Bally / Stern games. To be honest, it isn’t the best playing of the time. In my opinion Seawitch is a better playing game with a similar theme. The problem is that Fathom is probably the sexiest looking game made of that era. The color pallet and art package is just sooooo good. It is the crown jewel of most collections and because of that, it isn’t going to go down in value.