Of the 3 Ballys in your collection that I played a lot in my lost arcade years long gone:

Star Trek was my favourite for a relaxed and sane play. I could never stop at just one game. Beautiful, smooth player.
Flash Gordon was for times when I wanted a challenge and something to keep me on my toes. I gravitated between FG, FP and BK at times like this when I wanted to bash something which offered a high difficulty.
Playboy was for the late nights in George St Sydney arcades (and there were a lot of them in the wild back then). A nice drink, an exotic French cigarette and many games on Playboy. Ahhh, those were the nights!
Your other 2 titles I also played but not as much as these 3.