I have done both so far, finish both 1st in guild groups on main. Finished ZA so far on alt and ZG all but 1 on alt.
Trash in ZA is only a problem if you let the gongbongers bong the gongs. If you have smart dps that can completely be prevented, having 2 less hard hitting mofos on your tank.
Update:
Right I was Royally pissed off with CTA in ZG, really pisses me off when it takes me 15min to teach a boss to morons just to have them ninja my tank loot. Left that group and put the ****er on ignore to be sure I don't group again with that toon.
Cooled down after 30 minutes of raging, then joined for another run, where we wiped on the 1st boss, but after that it was a damn decent run after everyone got over their egos, which got me a nice 2H weapon from Jindo. Funny thing is, I joined that ZG with CTA, but then 2x DPS stayed on for another run, where we got ZA, almost made the bear run, just 1 mistake with CC screwed us over, but again I got the CTA reward, was pretty cool cuz I got a tiny raptor pet.