Some things I've noticed regarding the AI personalities:
Personality 10 (Iconians and Torians) is what is responsible for the bug where those races don't develop some of their planets. It's not the tech tree as some have suggested - I created a custom opponent with Generic (11) personality and the Iconian tech tree and it used all of its planets fine.
The favored ship types of a race are based on its AI personality. 8 is the only one to make extensive use of Huge hulls and generally tends to favor capital ships. 10 uses Tiny hulls more then any of the others do and generally goes with a "zerg" strategy of large numbers of small ships. 11 and 7 generally use Small, Medium, and Large hulls only, with 7 using more Medium then Large and vice versa for 11.
Switching races with personality 7 to another personality definitely improves their colonizing. Since I don't play Metaverse, I edited my Drengin (the worst offender in terms of not colonizing) to use personality 11 while still using the Drengin dialogue tag, because the Drengin tend to have a lot of unique dialogue. It led to a vast improvement in their behavior.
AI personality 11 is the "generic" one and works pretty well, although it is prone to one particular stupidity: the Korx and Altarians both will be building troop transports before they even have any military ships that can attack! For some reason this doesn't happen to the Arceans, although they also use personality 11.
From my test games, I think this is the product of the Altarian and Korx individual AI modules, not of AI personality 11. The Altarians and Korx, as well as the Terrans and Drath, will occasionally pursue a 'pacifist' strategy where they do no military research and focus on production. The Arcean AI, despite using the same personality, is much more militaristic. Some other features tied to individual race personality include the Korath use of spore ships (setting them to Drengin or Yor will cause them to use transports instead) and other SA-related behaviors. Additionally, the Drath AI appears to heavily buy other races' ships, which isn't done by any other race using personality 8.