In the year I've owned the Vita, I've played 55 full/PSN games that have a trophy list and platinumed 17 of the (soon to be 18). This does not include upcoming purchases such as Spelunky next week or Muramasa (and maybe Dragon's Crown/DoA5+ tomorrow).
I have owned a 3DS XL since May. I have acquired pretty much every game I could ever want in it's library already (with the new Zelda releasing in November). I even bought a few games like RE:Revelations because I got it for $10 and didn't want to pay $50 for the PC version yet. With all that in mind, the total games I have or am interested in (not including Zelda or Mirror of Fate [which just got an HD port announced]) on the platform is 10 or less.
Go figure. Everybody's different I guess.