Bah. All of the game's chariots are absolute rubbish. The only exceptions to this rule are;
British Light Chariots. They're just as bad as other chariots but in their theatre (Barbarian west) their arrows are rather effective and their mobility more of a plus. Just don't ever put them in hand to hand.
Egyptian General. It sucks having a general who can't join a mellee if things get tough, but at least he can be constantly firing arrows over your troops heads while stationed in the rear (not as cool as an eastern general, but still usefull).
Apart from that, all chariots are absolute crap because of the following:
Selucid, Pontus, Egypt: cavalry heavy regions make chariot archers worthless.
Pontus, Selucia: Scythed chariots behave poorly and often run wild for little or no reason.
Egypt: Heavy chariots suffer from everything their Scythed counterparts do.
The only exception to this rule is using Scythed Chariots for counter-charging through narrow streets in a seige. But even then cavalry are usually a better solution (or Elephants).