Thought I'd chime in a bit here... as I have a number of these.
Health of Target's Target is incredibly useful for both the healers timing heals (you can see if you need to throw a CH on the tank or not, depending on if the mob is about to die etc etc). It is also a wonderful pulling tool, as if you are in doubt on whether a mob is going to assist your pull you can target it while pulling another. If you suddenly see your name pop into it's target, then you have agro, don't even have to face it to see if it's moving towards you. Monks can also use this to see if FD wiped agro even if the target is blocked, can react and FD the second they pop up, seeing their mob retarget them the second they stand. Tanks also love being able to see when they are losing agro (mob doesn't even have to twitch a muscle, retargeting shows it has switched, and tank can taunt/stun whatever before the mob even gets a chance to turn around and whack someone else).
Deligate MA is useful for groups that have problems using the assist key, or in situations where you may fight many opponents, and the tank may switch around (without telling). It also helps to make the mezzer the MA person, so they can show the tank which mob to kill next very quickly. Kinda situational though.
Spell Awareness is amazingly helpful... by far my favorite leader AA. Useful for pulling, you can tell if and when a mob starts casting a buff (sometimes pullers get paranoid a mob is starting a nuke on em, if they are buffing instead, they can pull around the buffer while they cast). Very very useful for fighting clerics, as you can tell when they are casting nukes (let em) or complete heals (stop at all costs). Gate is already shown, but SA just gives another line of text saying, yes this mob is gating, stop him. Also helps stop other nasty spells, like dispel or mezzes... if the stunner/mezzer cares to stop em. (edit) forgot to say... it also lets you know what spells your group members are using, and if they're doing anything at all. I've actually had to correct a few lvl 65 shaman, who were using really low level slows, or disease based slows instead of their magic based slows... sad that they didn't know their own spell book (and e-bayers are becoming more frequent).
After those, I'd recommend hp, then attack. Mana is pretty much pointless, once people have KEI, amongst other mana regen, who the hell cares about another 100 mana? Noone runs oom anyways these days... unless someone's doing something majorly wrong. Gotta be nuking the heck out of something or healing a very low hp tank to run oom. And in those cases, you're probably over agroing anyways. That would be the last leader AA I'd ever get, and I'd have leader AA turned off a long time to get normal AA's faster first. Well, I'd probably get that before regen too... that's even more pointless. Another 1 or even 5 points of regen means nothing when you're getting hit for 200, even more pointless when you're getting hit for 1200.
Edited, Tue May 25 14:28:31 2004 by ZhaoVizier