I'm only on my first game, normal/normal difficulty, and I had to fight my way from lowest ranking to the top. It was a mighty struggle, and I sure won't complain the AI is fighting back.

But more on topic : a trend I spotted is a tendency for AIs to enter wars on the winning side, three of the five AIs declared on my first ennemy after I had slapped his army down. I also noticed Tarth got several war declarations after it became clear they were loosing against Kraxis.

So I don't think AIs at normal difficulty or under are programmed to dogpile human player, instead they dogpile who seems to be loosing a war. That and diplomacy allowing to buy someone on your side might explain why some get this feeling that every AI hates them.

I'm not so sure about AIs having bonus or not on normal, I'd trust the programmers if they say they don't, one must be very carefull during the first 50 turns as to what he is doing to keep up with AIs. (I did crap and had to conquer to come back on score)

Ythril : Remember it may seem great to have tons of juggs and armored troops, but you need light fast moving troops with high init as the core of your army, your faction bonus allow you to have tons of troops thanks to the reduced upkeep, plus your other bonus make even light troops dangerous. (+ 1 level...etc)

in my first two games, i got crushed utterly. everyone always seemed to expand faster and then all team up against me.

By my third game, i had learned how to design an overpowered sovereign. I got crushed in the beginning, and bullied by two empires who were each four times my size, teaming up against me. I led a four-champion questing party on a vanguard conquest, bringing two empires to their knees and getting into first place simply through combat tactics. And also through haste spells and a ridiculous amount of air shards.

But by my fourth game, i'd learned the economy. The critical importance of early land and resource grabbing. Of stockpiling crystals, wargs and mana, long before i'd have any need to actually use them. Of getting explorers out to make first contact with factions early on, and making deals with each of them before they could start getting cosy with each other. Non agression pacts and trade agreements will send your economy soaring through the roof

Now i'm on my fifth game, i can completely dominate the game in every aspect, and i'm starting to raise the difficulty to compensate ^^ it's been an interesting learning experience.

One important thing to keep in mind is that the AI has no morality. It seeks only power, and to win, not to act with any honour. It's motivated entirely by fear, and the only way to have peace is to be significantly more powerful than everyone else. Or rich enough to buy their non-agression pacts

Don't try this. I do not think AIs care about NAPs unless they are weaker.  I know for a fact that they did not honor NAPs in .982.