I haven't played either but I've been following Blazblue for a while. I'm very familiar with the story and character and play styles. But I'm worried the online scene may be dead.
Persona on the other hand, I know it's made by ASW and it's easier to get into from what I've heard. But because this game is newer I think it may have a larger online presence.
By the way, I play on Xbox if that helps anything.