I had both classes in beta. In pvp Mara kills faster and has many super useful abilities like 100% armor ignore, 99% damage bubble, force cloak (which gives you second bubble in annihilation), cloak of pain (very quick coodown if specced), speed buffs - all of these while doing high non-stop damage. And the only thing rage jugs can do against this is a good burst every 20 seconds or so. Also playing jug forces you to use guard/taunt and carry the ball, otherwise you will not utilize your fullest capabilities. While playing Marauder you can just kill kill and kill again.
Ahh yes, vengeance hybrid is gimped version of mara, because it doesn't have rage burst.
Marauder is a bit harder to play btw.