Flying mounts.
I think the LFR and LFD tools broke the game. There used to be a benefit to having friends and guildies and being an overall nice guy who would get invited back into groups.. Now it's just sign up by clicking here and act like a complete douchebag once you're in, since you'll never ever (ever) meet those same people again. So who gives a shit? Ninja everything you can, you can make a nice profit out of selling those items that those other people needed badly. Ninjapull the boss and be done with it, it won't damage you or your reputation in any way.
It ruined it for me, it really did. I miss the good old days where you'd get a bad reputation if you ninjalooted or committed some other atrocity.
2v2 arena.
Transmogrification and CRZ.
37 + (3*7) + (3*7)W/L/T/Death count: Wolf: 0/1/0/1 | Mafia: 1/6/0/7 | TPR: 0/4/1/5SK: 0/1/0/1 | VT: 2/5/2/7 | Cult: 1/0/0/1
Transmog and Achievements.
Karma always has the last laugh.
Transmog, hands down. A reason to do old raids to prettify yourself.
Ah impossible to pick. But well its not voice chat atleast xD And I'm no fan of arena even if its fun time to time, but I rather had the pvp more focused on battlegrounds or other things.