Principate
Saint Titanfall
Relative to hardware sales - yeah, Vita software had a much better 1st month than 3DS software. Not even close. But because Vita had so many more launch titles, the average Vita title only sold about half of the average 3DS title.
Fun fact for launch month (since this stat is almost always reversed for Nintendo):
3rd party average sales per title: 3DS > 3 x Vita
1st party average sales per title: Vita ~ 1.5 x 3DS
Oh, and for the only brand comparison available: Rayman 3D > Rayman Origins
TBF aside of Nintendog Nintendo purposerfully didn't bring their A game to the launch to leave space for 3rd parties.