How to get good generals in Centurion: Defender of Rome?

Yes, there is. If you start creating legions close to the beginning of the game, you are very likely to get the generals with low Charisma and Voice. In order to increase the quality of the generals you get, you need many victories (in either land or naval battles) against armies from countries that are both powerful and wealthy (Carthago, Macedonia, and Parthia). The game engine keeps a hidden counter of "Roman reputation" which only increases significantly when you win against these territories. This reputation stat influences the generals you are allowed to have under your wing, the likelihood that other countries will be willing to make alliances with you, and the morale of the peoples you conquer, among other things.

If you get 10-15 victories against each of the aforementioned really powerful countries, you will find that the game gives you much better generals than if your reputation is low. Reputation influences not only the generals you get when you raise a legion, but also the general who gets to command the Roman garrison against external attackers. If you play the game long enough, you will see that the program changes the garrison commander with every few victories. This means that the more reputation you achieve, the better garrison commanders you will get.

A few tips on how to get better generals:

1. Do not occupy Carthago, Macedonia, or Parthia too early. Remember you need them to send many marauding armies in order for you to defeat them and increase your reputation.

2. Hold off raising legions for as long as you can. This way, you will allow your reputation counter to increase as you win battles, and you will get better generals once you begin raising legions.

3. Before conquering Carthago and Macedonia, make sure you defeat their fleets that are moored at the beginning of the game. They are basically there just to give you a few additional reputation points.