iPhone!

No.  It's sketchy at best.

I would say that most of the important stuff is there.  The Monster Hunters, Grand Theft Autos, Metal Gear Solids and most of Square's stuff (obviously all of Sony's stuff as well).

But there are some really glaring omissions.  Crisis Core, Kingdom Hearts & Metal Gear Acid are the ones which stick out to me.  EA have also got 99% of their catalogue on PSN but have decided to make 0% of it Vita-compatible (at least in EU).

I vote PSP since Vita has no backwards compatibility

I voted for the Gamegear but I forgot about the iPhone/iPod touch, they are now considered a big player in the gaming handheld space.

The Tiger handhelds.

I woulda said iPhone, but you don't seem to acknowledge that as a gaming system.

Vita even ignoring backwards compatibility. Uncharted, Wipeout, Gravity Rush, LBP, Super Stardust Delta, Escape Plan, PSASBR, Mutant Blobs Attack, Sound Shapes, and Frobisher Says offer such quality and variety that they rival the PSP's whole library for me. Add in all the cool social features, I'm addicted to Treasure Park, and it hands down beats the competition. Hopefully when this generation is all said and done most people will agree the Vita was at least better to own than the PSP.

Vita. I don't need to own any of these to make a decision.

I say Vita.

PSP obviously, but GTA games excep Chinatown wars suck hard, ugly downports
other than that easy win for the PS portable