Best army composition for....

[konny]

I am not sure what you are trying to say. I merely pointed out that Hellenic generals did join in the fighting, unlike their Roman counterparts. Fair point about Hannibal, though.

The difference is that Hellenic generals usually fought leading the tactical reserves. They kept control on the battle until these were committed. In fact another saying is that once a general has committed his last reserves he can't do different than line up with the men. Another point with those Hellenic generals is of course the imitation of Alexander himself.

A Germanic general, for example, would have most likely to be found in the first line of the centre of his army, and so he would be leading the first full scale attack on the enemy. After that he would most likely not have been able to control the battle. In fact his subordinates would have had difficulties to even find their general in that chaos. That does not follow that they had been poor generals, it is more that the lads expected their leader to do so.

Another example for commanders leading from behind would be Xerxes and Darios (and with them probably Persian commanders in general).

[Ludens]

Alexander didn't use much in the way of reserves. His personal unit may not have been the first to engage, but he definitely didn't wait long to engage either. IIRC most later Hellenic generals were more cautious, but they still wouldn't have the same amount of control and mobility as a Roman general.

[konny]

His assault wing or the heavy cavalry, plus infantry support, under his personal command was the reserves - in tactical terms. The difference is, of course, that it was usually the only body that did actively attack the enemy, while the centre and the refused wing acted very passive. That's the difference between Alexander and, for example, Napoleon who prefered to attack the enemy with different parts of the army on various spots before committing the reserves.

[Ludens]

So shortly after the start of the engagement Alexander would have been somewhere in the enemy lines, and therefore unable to control the greater battle.

[konny]

The decision took place where he was (not because of his person, but due to the nature of the troops he commanded). The other parts of the line where a static phalanx and a screen on the other wing, neither of which needed any superivsion by the general. That all had to do with the composition of the army and the overall tactics. Hannibal, for example, would have never won Cannae had he commanded the Spanish cavalry in person.