Official wise, stick with battlefield I'd say. The low platforms let their high range attacks (up-smash!) get them pretty much everywhere, while the flat ground has no chance of blocking aura spheres.
As for counter-pick, and I can't believe I'm sharing my favorite strategy, if green greens is on for counterpick, USE IT. Learn to use the bombs to your advantage. I don't know about marth, but on the side platforms, lucario's ledge attack reaches all the way across. If there is a bomb right next to the side platform, go next to it. Predict your opponents attack and counter. They will hit the bomb, have a great chance of dying, and you will counter safely. (also, chain force palm grabs against the blocks works very well against heavy characters)