I've pvped quite a bit with my jug. I have two full sets of champion gear, and have tried all three specs.
My favorite is still immortal spec with vindicator gear.
The spec speaks for itself in my experience. I'm by no means a pro pvp player. There's nothing really exceptional about how I play. I even click some of my non-rotation skills. But, I hear from a lot of players that they hate facing me the most in warzones.
The spec:
-tough to kill
-surprisingly decent dps
-can 1v1 most classes (however, its often a stalemate against a good healer.)
-2 stuns. 3, if you count force push. 4, if you count intimidating roar. 5, if you count force leap.
-a free spammable slow
You won't be blowing people up left and right, like you would if you were rage spec, but you will be a total pain in the buttocks for the other team, and a huttball god.
Use guard, taunt and intercede(lots of medals) and lock down enemy healers with your cornucopia of stuns and interrupts.