I guess it depends on what level you are. But for me the MOST useful AAs i use are the Gift of Mana line...it is awesome! Obviously Spell Casting fury (more crits), destructive fury (harder crits), improved familiar AA, Nexus gate AA is a Godsend (also exodus- i have both because I like exploring or trying to be badA). Harvest for mana....etc.
For me, anything that increases crits and mana is a must. But you also need to get runspeed and some other foundational AAs, like raising your base intelligence (which is awesome too by the way). I haven't gotten it yet because I'm obsessed with making my crits, but Spell Casting subtlety would be a great one if you group a lot. Perfected invis is also nice to have....Anyways, they are main ones that I use constantly...especially Gift of mana..it changed how many mobs I can take down before meddding (if I ever have to).

Hope that helps.

PS - I'm all for resurrecting these boards!!