I don't know. Resident Evil and Tomb Raider sold me on the PS1. Zone of the Enders (with MGS2 demo!) sold me on the PS2. Metal Gear Solid 4 sold me on the PS3.
Sony has some great franchises. I probably would have gotten a PS3 for Uncharted 2 if I didn't already have one but part of me can't help but feel that Sony has franchises that sell to Playstation owners instead of franchises that sell Playstation consoles. I mean, if Sony has such a franchise, why don't they use it to sell the Vita?