I think the implementation of T3 air is by far the weakest fundamental part of the game.
T3 air is practically invulnerable to everything that is not T3 air (with the exception of static T3 AA). Achieving T3 air superiority consists of spamming a single unit. (boring).
It leads to unbalanced strats where for example a single strat bomber just kills the enemy if he doesn't also have T3 air. Rushing T3 air is a no-brainer on any map larger than 15x15 or a sheltered air position.
It isn't a simple matter of rebalancing, it is a pretty fundamental flaw in the way the interactions are set up. It would have been a lot more interesting if there for example was a conceptual AA gunship (not the current restorer) that was superior in AA to ASF's, but slower. It would present an actual choice between mobillity and firepower.