They are two sides of the same coin. They're both perfect just in different ways.
Green Heart is perfecter. Her voice, the way she talks, her green hair tied up in a ponytail. Everything is perfectly tailored to my taste.
Vert is still great but Nowa, Iris Heart and Purple Heart are better than her.
I've never really cared about Neptunia, never played a game and dropped the anime about 4 episodes in but I really need to ask whats the point of those transformations? The designs are ugly, they look like literal prostitutes and I remember their personalities changing but my memory might be a little fuzzy on that, but the thing is what purpose do they serve other than making Neptune better than the other girls for no apparent reason?
I would put Mina equal with Chika but that's probably just me having weird taste.
Original Nep is best Nep