While Ram, Pocatello, and Hiawatha may be annoying forward-settlers, they're usually not super aggressive and march armies to your front door because you forward settled them and they denounced you five turns after you met, they aren't nearly as bad as Alex. Also, all four of them usually aren't real threats to win the game, they over-expand, and Alex and Ram specifically dump to many resources into CS's. Also, Pocatello, Ram, and Hiawatha are easy to get DoF's with usually.
Warmongers aren't fun either, whenever you try to go peaceful and get your science up, you get an army at your doorstep if you're not willing to bribe them to attack others. That's what makes them non-threats though, you just pay them 5 GPT to attack a neighbor, by the time their special UU's are ineffective you can take them on the battlefield. Genghis, Attila, Ashurbanipal, and Shaka all lose value significantly after their UU's are obsolete. You can usually take them easily if you haven't already by the time you reach Dynamite. If they conquer an AI or two, they'll be struggling with happiness, so you can just get a few great works, pick a different ideology and tourism bomb them until their cities flip to you.
The real threats are the good AI's, like Russia, Rome, Germany, Poland, and oh that bastard Sejong. They get their science up early, tank, expand, blob and then snowball. From then on they pick their victory type, and your window can close very early, made much harder if you have Sejon's Hwacha's raining death down on you.
My favorite neighbors, when warmongering, are the wonder-spammers, thank you Ramsees, Enrico, William, how nice of you to build Notre Dame! What a nice gift.
When your peaceful, my bro has always been Morocco, if you don't step on his toes he'll likely throw you a DoF, and he's quite loyal too. But America is the king of loyalty, he's a bit harder to get a DoF with, but once your friends you're bros for the game. But if he hates you, he'll hate you. Pachacuti is another friendly guy as well.