depends on the mod. ironforge for instance is super geared towards flippers since bursts are so powerful. the stronger the bursts are, the higher the arena wall needs to be. something like the BBEANS arena v2 with higher walls would be one of the more balanced arenas imo, especially with the middle hazard that helps break up wedge wars.
also depends on if you use ai or pvp, pits in pvp are far more balanced and less random than with ai