You'd really choose a Vita over a PS4? I've had a Vita since launch and I can tell you first hand that it's a pretty depressing machine. There were a few decent titles at the beginning like Gravity Rush and Wipeout, and more recently Killzone was pretty good, but other than that it's been pretty much dead.
PS4 on the other hand has no chance of suffering the same fate, and is guaranteed to provide a steady stream of AAA titles. (Just realised I sound like a PlayStation marketing guy, but in actuality I prefer Xbox)
The point is a main console is going to have lot's of huge games compared to a handheld, whereas the fate of the Vita is uncertain at best, with really really crappy support so far.