16GB - the minimum for your Vita

Possessor of two 8GB cards, we must admit quune 16GB card is the bare minimum as long as you use the Sony store. With good average 1.4GB play, not counting backups, you arrive very quickly to saturation and frequent changes of card, even forget which card is your game. No more convenient trips.

With 16GB, you begin to see the end of the tunnel, with a margin of safety that is felt in transport / travel.

Unfortunately, Sony has chosen the priority size and it pays. As lon is 20 micro SD card 32GB, 16GB for your Vita will pay more than 30 (still cheaper than in other stores, that they are in line or physical). Logically, this card will be specific to the Vita and may not be used for another purpose.
Moreover, it does not seem to shine by its performance. Too bad for a portable console that's worth it, having to pay for games / accessories (including a mandatory memory card) so dear!