Didn't think anyone disliked Overlord Prier, then again I don't care for Marona; personal preference (I found her whiny; Ash was okay though).
Of course naturally Etna is far more likely, heck somehow just Etna and a Prinny got into Cross-Edge (granted not a good game; in that the cut-scenes were great the gameplay was horrible; I'd rather just watch all the cut-scenes on youtube than play through it).
and then into Trinity Universe (which had Etna, Prinny, and Flonne).
In fact with as many cross-overs as Laharl is in, Etna and the Prinny have him beat as they have been in none-NIS cross-overs. Flonne might just be even with Laharl *not sure* while she was in Trinity Universe, Laharl had that voice-cameo in Soul Nomad.
I have thought of an NIS fighting game, (surprising how well they can fit into such a medium, even with their over the top moves; *even figured out how to have Laharl, Mao, and Valvatorez to all have sword specials and still be unique (mostly thanks to each game's different moves and different graphics making it possible to switch them up; even Blade Rush and Hurrican Slash. ) But that said Prier comes to mind immediatly for me with a fighting game thanks her fighting style being so easy to translate into a fighting game.
However that said for a big cross-over, the reps for NIS would have to be the Disgaea trio and the Prinny. But not likely to get all four (why I thought of moves using them along side each other), still Laharl and Etna would be nice as seperate characters (with the Prinny along side Etna as a side kick and ammo), Flonne as an assist move for both Laharl and Etna might be interesting (especially if one uses Fallen Angel Flonne and the other Angel Flonne).
Good? Evil? I am what I am; a force of nature.
Overlord? Diety? I wasn't aware I was in charge, I am just the creator.