ShinKroller on 19 December 2015
I can only vouch for disgaea 4 since that's the only one among the 3 i've played so far. For disgaea 4 you have an extra story dlc for fuuka and desco. If you happen to like them both, then you might enjoy it. On the other hand, Disgaea 4 vita has an extra story exclusive for it and also has the cheat shop from Disgaea D2.
I personally haven't played both of the dlc myself since I recently changed to the Japanese Vita version.
