The secret of Hiawatha is to throw the hell out all this expansion penalty nonsence as take every tile in the universe. I "banned" this bastard from my TSL maps (i mean, created by others true start location maps in which I change civ rooster to my own preferences) to avoid Iroquis being in the middle of Sahara, Siberia, Australia and damn continent of the magical dragons. I know that such continent doesn't exist, but probably this crazy bastard is even there. The worst thing in Hiawatha is that this sociopath lack empathy and basic understanding so much that he never realises I hate him, and always is neutral towards me.
It's not just his CS allly flavor, it's something else besides that, nobody else combines better expansion, warmongering and diplomacy. He seems to be one of the few AI that has the priorities right.
That's funny, because in my Civ "career" I have never ever seen Alexander achieving anything, he is always the biggest idiot both in diplomacy and in warfare, who begins ridiculous war, loses it and is gangraped by the whole world

One time when I was playing on earth huge map as Arabia this moron started the war with Rome and sent all forces to... Siam, through the worst terrain possible, and its army was massacred by Gandhi (if your army is massacred by Gandhi, you really suck) and barbarianns
Besides Alex I am only seeing consistency from Shaka, Atilla and Bismark. But they do lack some finesse in diplomacy (although Bismark does a great job as well).
Attila is too often passive, despite he has most warmonger - designed nation ever. Shaka is absolutely terrifying, either he becomes world's Adolf Hitler (seriously, few times he was making regular genocides, with infinite city razing) or at least makes little genocide in the early era. Still I love this guy and his civ
However, there are two true masters of AI in this game - Bismarck and Catherine. Their capabilities, at least in my games, are just ridiculous. Germany and Russia always become either total runaway empires or at least Very Nice Strong Countries, with giant production, GDP, terrifying army and good science. Also, I am nearly always the greatest friend of Catherine and the greatest enemy of Bismarck. Last time he become hostile two turns after I met him

(and I was Poland

)
Also, Sejong is tall science master, Darius is wonder grabber, Dandolo does suprisingly well with these few cities, ar - Rashid creates powerful economy, and last but not least, die Hiawatha and burn in hell, you bastard!