I bought Civ V around this years summer when there was a nice deal for the complete edition and so far i had great fun with the game. Never played a Civ game before and i'm up on Emperor Level now.
Okay, which AI personality annoys you the most is the question? Hmm ... the top 3:
Inca because they always seem to do really strong, at least in my games. Grow fast, many cities and if they are on a different continent they war and wonderspam at the same time succesfully. It's challenging yeah, but quite frustrating too especially if you are lucky and get him in 3 of your 4 last games.
Then Japan just because he likes to declare war to me without any 'real' reason. I had him as my next neighbour in a game, as a far away civilization and the last i met in another and however he just attacks me even then when we don't have a negative diplomatic status. In every single game i had to go mad at him at some later point and nuke and raze everything just out of principle.
Place 3 goes to one of the more religious Civ's but i can't really decide. Ramkhamhaeng maybe but i don't see him that often. It is annoying keeping a nice religion and constantly seeing GP's and Missionaries. Haile Selassi and Pacal are spreading religion too in a heavy way - - - i don't like that because you are forced to keep the army so they can't get in or buying Inquisitors with faith instead of Great Persons or Buildings usually exactly when you need them.
Never had a problem with Alexander who seems to get a lot of hate. The other typical warmongers are usually loyal friends to some point, but i think it depends on difficulty level a lot. Until now i don't have any experience with a diety level Shaka or something. ^^
PS: Sorry if some things are spelled wrong, my english is a little bit basic but i hope you understand what i'm trying to say. This Board is full of great strategies and i learned a lot just reading, now i wanted to share some of my thoughts.