Three games? Hmmm. Do I get just the core rulebooks or the supplements/adventures/accessories too? I'm thinking what would give me the most stuff and the most variety of gaming for the longest time?
1. Something suitable for multiple genres. I don't want to be stick in one style of game forever. There's GURPs, Savage Worlds, newer stuff like Cypher or Genesys, a ton of stuff, but I would have to go with my own What's OLD is NEW. Gives me fantasy, modern, and sci-fi at the level of crunch that I like.
2. Something quick and easy, rule-light. There's a billion choices there. I'm gonna go Dread, assuming I get a free Jenga tower with it. Second choice would be my favourite game the Ghostbusters RPG, though that's a limited scope experience.
3. Something big. That way I get a ton of support materials and stuff. I'm gonna go D&D 2E for that--not for the core game, just for all the other stuff. The adventures, the battlemaps, the settings, the accessories (do I get the novels too?) -- there's just so much D&D 2E stuff.