It depends upon your matchup, if you're against a power character, gadget character, or acrobat.
Acrobats best stage is Watchtower- for it is the only stage in which they can use interactables almost as well as the rest of the cast: for everyone can throw the drones. Always.
Gadget VS Power is either Crime Alley, for dumpster OTGS that power characters can only dream of having- and being able to use the dumpster repeatedly.
Gadget VS Acrobat is Wayne Manor parking lot, easily. The Gadget character can use the car on the left an infinite number of times, for 20% unclasables, combos, and corner escapes-- and the only interactable from which acrobats get damage is the motorcycle. Slow.
Power Vs Gadget and Acrobatis either Gotham Rooftop, Lex's Lab, or Metropolis Rooftop/Museum. Lots of fast throwable stuff, and near nothing for other character types.
Power Vs Power doesn't matter. Play whichever you've made combos for.
There are some character specific best stages.
Catwoman rocks Atlantis: (See
Under_The_Mayo 's science of interactables video.)
Cyborg and Shazam do amazingly well in Fortress of Solitude, as they both have inescapable, colossal damage from the rocketship on the left. and Harley and Joker are usually best in Wayne Manor's Great Room, they get 22% bonus damage from piano combos, a chandeleir to help against zoning, and two corner interactables that lead to unblockable setups. Oh, they also have crazy chair tech. seriously.
