Most of these buffs are pretty nice. How nice you think they are depends on your spec, and also your playstyle. A few of them are not all that useful, but again I'm sure that is influenced by the fact that Morn is a tank and Kuan always runs around with her. So we can quite easily and quickly aoe down large groups of mobs.
However my favorite, the bestest buff in the ENTIRE world, is Iron Mantid. It's an enhancement given by Malik the Unscathed. He is the second Klaxxi Paragon you bust out of the amber, and this buff is one of my favorites in the entire game.
Absorbed, blocked, dodged, missed, parried, redirected, reflected, and resisted attacks against the bearer cause Bladeturning.
Upon reaching 10 stacks of Bladeturning, deal damage and stun all nearby enemies.
This is the buff of tank AoE heaven. The more mobs you pull the faster they stun themselves. You're only limited by how many mobs you can get together at one time. And with all the groups, patrols, and fast respawns in the Dread Wastes that is not much of a limitation at all.
I just wish there was some way I could pick this as a talent for regular use.