Wayne Manor has the best music, in my opinion, so I typically pick that one.
My favorite is the Hall of Justice though, as Raven can abuse the interactables on that stage more than other characters, I think. Makes for really nice mind games, and is a good way to cover up some of her weaknesses.
Atlantis is another obviously good choice, it is a beautiful stage with a very balanced set of interactables.
Batcave is another amazing stage too, especially for power characters, as they can extend their combos and setups a ton using the wires in the lagoon.