If you are catering to pinball enthusiasts then the top 20 on pinside is a great place to start. Buy some of the games that are less likely in players private collection and you will do well. If your location is not know for pinball players then theme is your best friend. Star wars / Guardians / Deadpool. What you are looking for is theme mass appeal. Also look to do something to draw attention to your game. All the action is in the playfield. Speaker lights animated LCD and a flashy topper always increases visibility. More visible = More Money.
Games are very location specific. Consider the following: Not to easy in fear of long play times. Not too hard Don't want people to get so discouraged and not replay. Position in the room for maximum exposure is very important as well.
These tips help my locations. Hopefully they can do the same for you as well. Good Luck!