Ok I'll help some of you out because this is making me angry.
Root's both of the Warriors AC are messed up by root's. They can't force leap out of them so use them and **** of melee range. Simple really.
Crouched (sniper and ops) this effectively stops a warriors charge. Sages and BH knock them back as soon as they get in range. I'm talking ASAP, before they hit the ground if you are good. This will stop them from putting dots on you and you can snare and get back to shooting them. Their interrupts 4m so they have to be in melee range to stop your casts.
-Accuracy,
most classes have abilities that reduce Accuracy but very few people use them. Kill their accuracy and watch an annihilation marauder blow 5 rage on a hit that does no damage
-Ravage,
I have no idea what bioware was thinking when they made this ability uninterrupted while making it so you can't run out of range of the second attack without force speed or stealth. You really REALLY don't want to be hit by a full ravage ever... unless you are a tank then white damage really doesn't bother you. CC a marauder and be careful not to give them resolve before they use it because otherwise you are in for a world of pain. Also if you have an evade bubble use it and then you don't even need to cc!
-Undying Rage
this is a really easy one to counter, marauder hits 30% life cc him and finish him off. It costs half of a marauders remaining life to use so it will nearly always be used as an o s#*t button. I find KB's for ravage and stuns to stop Undying are the best option, if they get it off simply root them and run out of range count to 5 and hit your finisher.
-Force camo
not a heap you can do against this except know that the mara is either going to run away or use it as a gap closer. Options are either keep running or guess where he will come out of stealth and finish him off.
-Cloak of Pain
if you have a long root, stun or something that you can spare use it. Maras are squishy as f*#k without cloak having their defence effectively cut in half. If you catch it as soon as they put it up they have to wait 54seconds again to use it. Going into stealth for a little bit to wait for it to go off also work's. DO NOT DOT a Mara until they have used it or else you have just given them free refreshes for the length of the dot.
-Dots
Cleans the darn dot's, this is a massive one as most of an annihilation marauders damage comes from them along with their healing. Heaps of you have the darn ability so use it, their dots are on cd for 12seconds so you can effectively shut them out know what the dots look like and cleanse them as soon as you see the stacks.
For a class that is meant to be OP I see more bad marauders then nearly any other class in the game, these are people in full WH gear that completely suck and would be lucky to get 6th on damage. I also find most people have no idea how to fight a good one and get destroyed because of it. I hope this helps them and stops some of the QQ because honestly I don't have any issue fighting marauders on any of my classes (Sniper, Sin and my Mara)