Honestly, based on what I've seen, I don't think this game has an aggro table at all. I think it's entirely based on temporary taunt effects induced by abilities, if none of those effects are in place the monster just picks someone.
It's because tanking and threat doesn't work the way it does in most all other MMOs these days. I actually think the "Holy Trinity" factor in this game is pretty bad, from what I've been able to see so far. As a tank, I'm basically a guy that takes a lot less damage, but deals a lot less as a result, and due to the "threat" mechanics (or lack thereof, to be honest) I'm not even preventing a lot of damage, since I'm only effectively holding one or two mobs at a time. I can't even hold boss aggro consistently, and range DPS doesn't even need me because of how easy it is for them to kite stuff in this game.
As a tank, so far, I don't feel like I'm even necessary in this game, from a single-player or group aspect. My survivability isn't that great in solo content because despite higher mitigation I don't do much damage, and I *have* to stay in melee to kill, and I feel severely underwhelming in groups (when I've been able to get group dungeons to work). Better to roll 2 range dps, 1 melee dps and a healer, from what I can tell.
I think they focused more on the faction PvP than they did on PvE group design. You really can't split your focus in MMOs, and this is showing why. PvE might as well be an offline game.