Looking at scales and organization somewhat evades the key question of command and control; and with it its friend sequence of play. After all, it's the failed command rolls that were driving me nuts in my last BKC game -- and for that matter in playing black powder. It's not that I can't stand having some restriction on what my toy solders do on the table, it's just that some system are so frustrating.
I have played many randomness-free C3 systems over the years. In many ways written orders (early WRG rules, and Charge!) and simultaneous resolution are best. They have real advantages for solo play, but with a lot of units to move I've found that my decision time was limited to the first few minutes of each turn. That's the most significant thing that pushed me away from Command Decision.
Lately I have been looking at Megablitz. It is a stand=battalion games that aims to play very large actions spanning several days. The interesting there is that action is restricted by state (using the acronym SMART for Static, Mobile, Attack, Retreat, Transit). A unit can only move and act in ways appropriate to its state, and legal state transitions are restricted by current state and supply factors.
Restricting action based on state (stance may be a better word) should allow a more open unit activation system.
A big question about good brigade activation systems is "how many players should be able to play at once?" One-command-at-a-time is great for solo or two-player but falls flat on its face when half a dozen people are playing -- too many people are just standing around. A good system gives everyone at the table something to do.
One system I have in mind I saw used in large, multi-player refereed skirmish games. Each character was given a number based on his ability. As the referee read the numbers, a player with that number could undertake an action but a player with a higher action could interrupt just before the low-numbered player acted and take his action instead. Once you acted that was it for the turn.
That could be adapted by assigning proficiencies to commanders, keeping the range low to allow multiple moves by one side, but using an initiative system so, for a given value, either one side or the other is rated higher for the turn.
I have a game called Tomorrow's War on order. It is another skirmish system, which features an action and response system that might work for WWII. Shipped, so I will have a look next week.
And of course there is always good old alternating move, roll for initiative, with opportunity fire. It has some interesting variations which intensify fire -- probably a good thing for a WWII game.