Looking for a handheld console

Okay, hi.
I've almost always been gaming on PC. I had a few consoles back in the day, like the the SNES, the GBA, the NDS, PS1 and PS2. After the PS2 I haven't really had any interest for consoles as I had mostly been gaming on my PC and have been upgrading it over the years. Although I have a shallow idea I haven't kept myself updated with the console scene at the moment. I've been travelling a lot lately so I thought to myself - why not get a handheld console? So - which one would be the best for me right now? Which handle console has the most number of titles? Any info would be appreciated.
Thanks.

Nintendo is generally considered the king of handhelds so I'd say whatever the new/recent DS is.

I had a PSP. I loved it. It was stolen from me. I still love it. It is really old tech, though... I couldn't connect to wifi networks, because of the old tech in the PSP, the screen is low res, but i can't lie. I just loved the damn thing. The new 3ds basically is more powerful version of the old 3ds, so it have really rich library of games.

the nvidia sheild is your best bet. no doubt it has the raw power needed to emulate all handhelds not to mention having it's own exclusive titles and games from the google play store.