Bruv, at first I was kind of surprised that everyone flocked to LW. To me MW has the best matched plane set of all arenas. Inherently I feel the German planes have the advantage in EW. By mid-war most of the allied planes were well matched to the German planes. By late war Germany was falling behind in both quality and quantity.
But then when all planes were enabled in LW, it made sense that everyone goes there. When they did that, they created a mini old style MA.
So, here's an idea for all arenas. What if you take the actual percentage of a particular plane that was made in WWII and apply it to the arenas? Something like the Tempest, we know about 800 were built. For arguement sake let's say that's 1% of overall fighter production in WWII. Apply a 1% limit in the arenas. So, if there are 150 people flying in an arena only 2 Tempests can be in the air at one time. Apply this to all planes and you pretty much even things out. This might cause people to explore the other arenas. And it would provide a more realistic fighting environment.
Or carry it one step further and enable plane sets by country. ie: Axis=Rooks, Allied= Knights, US=Bishops. That also might spread things out a little more.