I think it's been a few weeks now since the "new and improved" AI for wars, dungeons, and PVP was implemented.
Since that time, I've observed a few things.
Any sense of randomness is gone. It likes to pick certain attacks over and over again. These choices are usually not a good choice based on the situation.
The AI prefers a defensive stance rather than an offensive one. For example, when I use my Arch Knight in dungeons with auto battle on, it keeps using Protection Aura over and over again rather than choosing one of the other three attacks, which are all heavy damage attacks. With Kihaku, it wants to use Kiai (regeneration to all allies) rather than one of the other three choices, all possession/freeze attacks. In my experience, a defensive stance in this game is a good way to get yourself killed most of the time. Now maybe this is intentional. Maybe SP wants to give more of an advantage to the attackers in wars and this is certainly one way to do it. I have, however, found it tougher to Autobattle in dungeons now as well as a result of this.
For monsters that have no defensive ability, the AI does always start the battle with the same attack. It's not usually my first choice either, but the AI is fairly consistent. In fact, it's way too consistent for me to believe there is any amount of randomness left. After lots of observation, I'm unsure how the AI chooses it's first attack when there isn't a defensive option.
Lets say you are working your way through a dungeon and you switch out one of the three monsters. This can totally change the attack choices of the other two monsters. Again, it's not always a logical choice of attacks but it does change and will be consistent again.
My observations are, of course, based on dungeon adventures, since it's more difficult to observe trends with PVP or wars.
It's like the entire system is trying to be intelligent but is failing more miserably than if it were simply entirely random.
What have others observed?