I think that's an interesting question. But I think the only accurate answer is not an answer at all.
Let me explain my rational:
Modern warfare relies on combined arms tactics and CON is true to this as well. This means that no individual unit type is greater than the sum of the entire battle groups parts. One unit type will always rely on another for its completion of the objective.
Artillery is only effective when supported by combined Inf. and armor to provide blocking groups and A.A. to create a safe envelope of airspace protecting said ground units.
That being said, Spec ops are very effective in limited rolls. But for my money Combined battle groups where all units have air-assault capability are very hard deal with for any defender.
but, that's just my 2 cents' worth