Elizabeth - one of the weirdest AIs in the game. If I get "guarded" diplo with her, I'm lucky. Settles right in front of my capital then keeps complaining not to settle near her cities. Then she denounce, declares war and wait for her CS to do the dirty work. It's one of those civs that I just love to stomp.
Ethiopia - Spams cities like crazy and loves to spam his missionaries and prophets all the time. If I want religion in my game, I usually like to cripple him very early on.
Oda - Turn 15, he already dropped city next to my capital. Turn 25, he already dropped another. DOWs, attacks. And he's one of the weird AIs, he is always at war, but you better not DOW anyone, because he will brand you "warmonger" and remain hostile until the end of the game.
Alex - the only AI that seems to have some brains and logic. I will rarely go into conflict\war with him early game, but I love paying up other AIs to attack him. Usually they don't do much, but at least they slow down his permanent CS allaying.
Siam - "I love to beat up my neighbors but you better not DOW anyone, or else I am gonna hate you till the end of the game". Plus, he's a wonder spammer and usually brutalize with culture.
Isabella - she's more of "annoying little sister" type of AI then any real threat. Not very bright, even when odds are on her side (like having few NW in her land). I see that she likes to bully Venice, but fails to conquer Venice EVERY SINGLE TIME (even in early game).
Napoleon - he's not much of a threat because he likes to attack early on so he is easily fend off, but he attacks all the time with no real benefit. He just kills off my trade routs and breaks research deals. But hey, he likes to give me lot of luxuries and GPT for peace deals, so, go on, be annoyance.
Hiawatha - Wonder spammer, city spammer. Backstabber. Likes to bully and beat up weaker civs.
Ramses - very cranky guy, usually "neutral" diplo at most. Likes to spam wonders and spread his stupid religion (usually useless)
Bismark - Very annoying, will denounce for no real reason. Will DOW then do nothing, or attack with his UU in Atomic era!? (seriously!?)
William - annoying guy that usually hates your guts, but will never attack. He'll try to undermine you with World Congress, like banning every single luxury you have. Sneaky bas.
Harald - cranky guy that rarely does anything useful. I've often seen him spawning right next to Attila and gets eaten alive.
Askia - The Freedom Culture guy that still tries to take over the world. If he stays alive long enough, he manages to place his 4th city.
Babylon - cranky guy. Hates me from turn 1 we meet. Places his cities on some stupid location and never really uses his HUGE advantage with GS. :O.O: