Honestly, I think all of them are genuinely best friends. Do they each have their quirks? Yes, but I think they all realize that they're stronger for them. Sure, Hunters may take jabs at the scholarly pursuit of the Warlocks, but when they run across something they've never seen before, they won't hesitate to ask. Warlocks may occasionally make jokes about the musclebound tendencies of Titans, but deep down, they respect the Titan's stalwart defense of the walls. Etc.