This isn't a balance discussion because the problem isn't balance, it's fundamental game design decisions. I think T3 air is just fundamentally broken in it's implementation. The primary reason is that there is only one unit that counters T3 air, namely the ASF. It all just comes down to building as many ASF as possible. Strat bombers are only countered by T3 air as well, If you don't have T3 air when a strat is out you basically lost the game, there really is no equivalent for land and sea, lower tier units there remain at least somewhat effective. The dominance of T3 air drowns out investment in T2 air because all investment there is undone as soon as T3 hits the air. Yes you can counter T3 air but it all gets funnelled into one solution: Make more ASF yourself. I think it leads to one dimensional play. Sure there will always be some strategy about when and where to engage but it will always be limited.