Uncharted doesn't stand a chance since it's free on PS+. I'm enjoying it right now even though I haven't bought a retail copy. Well, I plan to stay 100% digital with my Vita anyway, so won't be helping VGChartz numbers anyway.
Wii U will get there first. It's hard to tell which game will be the first Vita game to sell 1 million. It will probably be the next Uncharted or the recently announced Kojima game (if it really turns out to be a PSV game). Maybe Soul Sacrifice if it sells really big in Japan, but I wouldn't count on that.
Wii U is a GCN 2 - I called it months before the release!
My Vita to-buy list: The Walking Dead, Persona 4 Golden, Need for Speed: Most Wanted, TearAway, Ys: Memories of Celceta, Muramasa: The Demon Blade, History: Legends of War, FIFA 13, Final Fantasy HD X, X-2, Worms Revolution Extreme, The Amazing Spiderman, Batman: Arkham Origins Blackgate - too many no-gaemz :/
My consoles: PS2 Slim, PS3 Slim 320 GB, PSV 32 GB, Wii, DSi.