I'd take the PS2 if it came with a giant catalogue of games. Depending on where you live, all PS2 games are obsolete, besides the crappy ones like outdated EA Sports games and movie tie-in games that Wal-Mart/Target/Gamestop can't sell.
On the other hand, the 3DS doesn't have a wide selection of games to date, but I'm sure it'll grow. You just have to be patient with it. List all the 3DS games you have.
My final answer: Go without anything for now. Think about your purchase, and its level of urgency. Having an impulse buy of almost $100 is a terrible thing to do.