The Wii seems to be the most logical choice for Persona 5, since it's easier to develop for and costs less to develop for than the PS3. Furthermore, Persona is a game that relies heavily on its art style, so having more realistically rendered people isn't a must, since it's usually a hand-drawn portrait that does the talking. And considering the Wii is about twice as powerful as the PS2, I think that leap in visual power is good enough.
That said, I would love to see it on the PS3 with really nice cel-shaded graphics like Tales of Vesperia's. But in either case, this is still a rumor from a totally random blog site that has multiple spelling and grammatical errors, so as a huge Persona fan I'm wary of getting my hopes up.