3DS.
Played Ridge Racer, Zelda OOT, MGS, NFS The Run, F1, Splinter Cell, RE Revelations, KH DDD and Mario 3D Land. I love the machine, but the glare is not great in day-time (apparently the XL is better), so I mostly use it when commuting in winter.
*Almost* got myself a Vita at launch but decided at the last minute to get an iPad instead. I am still very perplexed at what is happening with the Vita - the device is almost as powerful as a PS360 yet devs continue to bring out dumbed-down versions of their games on it. I really though that the Vita was going to make the 3DS obsolete within 6 months, but here we are today.