I recently got a PS Vita and there are a good bit of games that I do want for the system, but I think it's hard to deny the variety of games available on the 3DS combined with the quality of the titles themselves. That, and the fact that it is fully backwards compatible with the DS also gives the 3DS an extra edge against the PS Vita.
Don't get me wrong, though. The PS Vita is currently my go to system for playing the games I loved as a child (non-Nintendo). It also has some good newer games as well, but the 3DS clearly has more of these. SMT IV, Etrian Odyssey IV, Kingdom Hearts 3D, Kid Icarus Uprising, Fire Emblem: Awakening, Theatrhythm Final Fantasy, the upcoming Bravely Default, soon to be released Rune Factory 4, Monster Hunter 4 in Japan, E.X. Troopers in Japan, Resident Evil: Revelations, Mario Kart 7, Super Street Fighter IV 3D, Mario & Luigi: Dream Team... some of these share a genre, but they are also all very different from one another. Looking at the PS Vita catalog, it's harder to say the same (albeit it's a strong list). Though I do see the PS Vita lineup for 2014 to become much stronger than it is now.
edit: That list is also incomplete, but I was just making a point (and also including mostly games I have played)
