I like that the AI builds swarms of light frigates, thats good IMO. Light frigates usually own anything else in a stand up fight with other ships. Of course vs planet defenses they get owned, but it's a pretty good tactic for the AI to use, as they are best for planetary defense.
It would be nice if it used it's scouting data to decide what ships to build. If it sees you massing light carriers, it should get some flak frigates, if it sees you have a ton of gauss cannons, have it get LRM's etc. Haven't played the patch much yet, so if it does this already, ignore this post

. But as a default, since this is still beta, light frigates are the best bet of any ship to mass if you have to pick one.