In all my games, I have noticed that all the AI civilizations will pick the SAME weapon branch to research in a particular game. For example, In my latest game (1.0x.01) EVERY SINGLE AI EMPIRE has picked Missile weapons as its initial weapon choice.... that is all NINE of the AIs. Something is fishy there. I would expect to see a roughly equal split between the 3 weapon types. (assuming its random) The game before this one, I noticed that all the AIs picked Beam weapons. I notice this problem mostly in the early parts of the game.. later in the game, some of the AI's diversify depending on who is at war with who.