I voted for Miku since Skies of Arcadia is already localized anyway and it's still perfectly playable on the console wherein it was originally released. (though I suppose the same could be said for all remakes on the Vita.) On the other hand, Project Diva f doesn't really require any sort of localization since the amount of Japanese required to play the game is practically zero, but it would be nice to have it officially in English... and hopefully at a cheaper price than the Japanese release.
Don't really care for the other games in the list. --- Vitassurance: The Webcomic http://www.jaded-perspectives.com/2013/01/vitassurance-webcome-1.html
If I lived in the US I would ask for Miku, but from a business point of view it makes little sense given the very niche nature of the content(although given the fact the porting process would only consist in translating the menus and licensing the songs, depending on how licensing goes, they could make some easy but small profit). But I vote on PSO2. It's an excellent game that appeals to everyone.