I like mixing it up still, and like I said in the guild chat forum I don't think we're too far away from getting Ossirian down. We have yet to try Jindo the Hexxer too, who's supposed to be capable of giving some good players a run for their money from what I'm told.

Hakkar has plenty of stuff to upgrade a whole heck of a lot of us, so I still have a lot of enthusiasm for him. Hell, him and Ossirian are the only bosses that really have stuff I'd seek. I still want to see more Hakkar kills, and we're getting more efficient at clearing the trash in ZG to make the path to Hakkar quicker. 

Zul Gurub's becoming tedious as we're starting to get a strong base of players who're just not really interested in the loot obtainable from the 5 priests we have to kill just for a shot at Hakkar.  Ahn'Qiraj, in respect to Zul Gurub is still sort of new spice for us too. We just advanced past our challenges in Ahn'Qiraj a little faster than in Zul Gurub. 

I'm cool with mixing it up as we are, I'm not more partial to either zone more than the other, myself!