Also AI personalities are a tricky thing. Some AI's are horrible backstabbers - I think for example Asoka and Frederick (although it may be Peter) actually have backstabber personalities, it's just that they wouldn't ever build up enough military to start feeling frisky - one of my few military defeats (pre-Better AI) was to Asoka, who decided to backstab me with a large axeman horde he built for god knows what reason. I can probably try and reduce this tendency by tying in the old aspects of personality with the side effects of reducing aggression - for instance the "Train Unit" probability - those AI's with a high train unit.
Here are the "Bastard Charts" to show which leaders are the biggest scumbags, according to their probability of training units, their probability of declaring war, their probability of shamelessly dogpiling and finally their probability of declaring war at Pleased - the Total column is basically their "Bastard Rating" - the higher the total, the more likely they'll cause trouble. For all numbers, bigger means badder.
(A 0% of dogpiling does not mean a 0% of him dogpiling you - it'll just be a total war rather than a dogpile war - however 0% at pleased DOES mean a 0% chance of declaring war - it wont happen unless the AI decided to declare before becoming pleased)
The winner is Ragnar, being highest or highest equal across the board - except in attacking those he is pleased with (only one is higher).
There are some anomalies - Mehmed despite having SOME nice personality traits (respects friends) is actually a big warmonger - call him an Honorable Warmonger, Brennus is like his little brother. Don't trust these guys unless they're actually pleased.
Catherine and Isabella both have fairly low train units - but are also very shameless in declaring war, making them the incompetent backstabbing b*tches we know and love. However Isabella also has her obnoxious personality working against her - making her both more likely to declare war, and more incompetently (catherine is more likely to wait for a position of strength).
Elizabeth is generally peaceful, but does have a chance of declaring war at peace but more importantly has an incredibly high probability of sliding a knife in your back if you are distracted - Roosevelt has an identical warring personality (good job...), fortunately both these leaders have low unit training probabilities so they may be too timid to attack (which is why they are backstabbers). Asoka is also something of a closet bastard but does respect his friends. And actually many leaders, such as Mansa Musa, will just decide to up and attack people they are pleased with - the dice rolls make it that way. Just because SOME peaceful AI's will do this shameless backstabbing rarely, does not mean that Hatty or Ramsesses will - those two are much more pleasant (not all peacemongers are XML'd equally...).