As we all know, within a matter of months we'll be raiding Siege of Orgrimmar. And thinking of both factions uniting against this bitter enemy, with both having their own reasons to want to kill the bastard, which FACTION do you think deserves to finish off Garrosh more?
This is not about who you THINK will get the killing blow. This is not about which CHARACTER individually deserves the killing blow. But which faction do you think deserves to kill him more?
The Alliance has a longer history with him. Even in Wrath he was antagonizing us, though he hadn't done anything himself yet besides talk. Then comes Cata. Where he invades Ashenvale, intending to drive out the night elves. (More than once if the in game invasion and Wolfheart are supposed to be two distinct invasions.) He's mana bombed Theramore, tried to launch an assault on Stormwind (derailed by Vashj'ir) sent the Forsaken into Gilneas and tried to to take Darkshore through the Shatterspear Trolls.
But while the Alliance has had reason to kill him for longer, the Horde also have a number of reasons. He used the blood elves like canon fodder in 5.1, tried to have Vol'jin assassinated for not making monsters, tried to put the Darkspear under martial law, used the Kor'kron as secret police against his own citizens, and cheated the goblins out of some money.
So who do you think has more reason to hate him? The Alliance whom he has invaded on several fronts, or the Horde he has ruled like a tyrant from within?