3DS, simply because of the larget library of games and the more promising lineup. And it's about £100 cheaper as well, which doesn't hurt.

If the Vita gets 20 games a year, the 3DS gets 80. So, variety
Plus, Luigi´s Mansion, Monster Hunter 3 Ultimate, Animal Crossing, Castlevania, Brain Age and Fire Emblem are coming in Q1 2013

Right now, the 3DS has more games.

But, I believe the Vita still has untapped potential and they really just need some games to add into the library. The Vita is a really cool little system.

Depends, on which games you like more.

RPG, Action-Adventures, Rhythm-games (there is a ton of them these days), Platformers, minigames -> 3DS
Shooters, Action-Adventures -> PS Vita

There might also be concrete games you are interested in: Monster Hunter or Gravity Rush for example, that might influence your choice.

3DS

it has resident evil nuff said

But, if he does not give a damn about those games? (like me)

I can only speak for the Vita, but wow, have I really been impressed with the hardware. The screen is beautiful, the multi-touch is excellent, and the dual analog sticks really do make a big difference with gaming. It's just a really awesome device.

Honestly, if you have a PS3, then I suggest you go for a Vita, mostly because of PS+. I bought my Vita on Black Friday with three months of PS+ included and so far I haven't bought anything for it because I've been playing the Instant Game Collection selections. Mainly Gravity Rush, Mutant Blobs, and Final Fantasy Tactics, but Wipeout and Uncharted are up next. Of course, since you get the PS3 games as well, I've also been playing those. PS+ wasn't something I was really interesting before but now I'm a believer.

Still, as with any system, it's about the games you want to play. I bought my Vita mainly for Gravity Rush, Persona 4: Golden, and Soul Sacrifice (which looks amazing). Tearaway and Killzone Mercenaries were also factors.

Spot on

If you ever played these games, it is impossible not to be interested.´They´re sequels to masterpieces

Depends, if you believe in the potential of the PSV then it may be in equal conditions in a year, otherwise 3DS.