3DS. Vita has no games. The majority of what it has you can play on the PS2 and PS3 already.
The reason this argument is flawed is that it assumes the Vita versions of various PS3 games are significantly inferior, which was true with the PSP. This is not the case with the Vita.
In most cases I buy games on the Vita instead of the PS3 because they're equivocal yet with the advantage of portability.
This is true for Totori, Need For Speed, and several other games.
The Vita version of Sonic All-Stars Transformed is actually, in my version, the best version. It has a better frame rate than the console versions with only marginally downgraded graphics. It has 100% of the features, modes, and unlockables as well, right down to the online components.
So I don't really buy the "most of the Vita's best games are on consoles" argument, because the implication of inferiority is flawed.