One of them will definitely be Baby Pacman. The other two, maybe a light gun game and something that moves around, like a vehicle sim or one of those games where the seat shakes and vibrates.
Dungeons & Dragons - Shadow over Mystara
Super Street Fighter 2 Turbo
Mortal Kombat
Would be tempted to replace one of the fighters with the cockpit cabinet of After Burner but if I was limited to just 3 units, I'd likely go with those 3 just to make a nicer wall line-up. Same with Alien vs Predator which I almost also included over one of the fighters but the cabinet was rather ugly.
A Neo-Geo cabinet with Windjammers and Garou: Mark of the Wolves
Street Fighter III: 3rd Strike
A third one is hard to decide...so many options! I'd probably go with Battle Garegga.