The AI's initial preference is = rand()%3.

Me too, I've had everyone concentrating on missiles for the entire game, with the exception of a recent one where the Korx AI seemed to go for mass drivers in my border skirmish with it, mixed with missiles.

Yeah, I think what happens is that the minors always tend to go the missile route, and then the majors trade with them for the techs? Even if they have a preference for beams or guns, they're prolly going to go for missiles, in my thinking, because of the high damage per mount, early in the game. I've seen some variety with mostly missile mounts and then maybe one laser V mount on a Drengin corvette, but yes I've also had mostly missiles in my games.

I thought this too... for a long time it seemed like every comp opponent was going Missles. So much so that I would immediatly move to the missle defense tech without even bothering to see what ships I was up against.

All the sudden though...i rarely see missles and I see lots of beam weapons. I figure once I get to the point that I immediately start going for the shield tech.. they will switch to mass drivers.