ill chip in with MY Order warband list, someone else can do the Order 6man list (double slayer, or WL + ASW?)
Order Waband tier list:
S-tier:
Brightwizard. The class IS the meta both what Order builds around and what destro comps build against. Group-offensive damage procs, morale damage proc on Explosive force, a selfpump + offensive M2 drop, ranged morale drain, funnelpower, crazy value from onslaught boost proc + classmechanic and 360degree aoe spells plus good singletarget assiting damage while also being able to aoe silence a healer-stack.
Knight. additional healing to the party from Focused mending, Aura value without paying any attention to stancedancing or twisting, Banish Darkness superpunt away an enemy wbleader or mainassist, M3 No Escape, Solarflare meme for funnels since its never used or reached in the open field, Vigilance this tank just doesnt die before his guard. This Class also has a spot as 2handed for applying aoe Woundsdebuff
Book Warriorpriest.
1sec groupheal, group hots, strong singletarget ap heal to get heals out of two different resourcepools, strong prayers, group wounds buffs, eazy resource return with 24aoe cap smites or onslaught setbonus, medium armor and aoe detaunt survivability, matyrs blessing raidhealing.
A-tier:
Slayer. The slayer doesnt have the option to go ranged and kite as the BW, or as easy of a time to get morales in a siege, and has very limmited aoe use of his obtained morales. in terms of damage he lands on 3100 aoe dps presure vs BW 3500aoe dps presure from my internal tests so he is very close to same output when he is not out of AP. Shattered Limbs 24aoe target, strong aoe melee dps on top of a DPS runepriest aoe armor debuff makes for crazy aoe presure. Rampage for 20sec to lineup a big Retribution burst is deadly. We did run 6slayer comp for a periode before everything turned right into everything being based around morales, and this bring Slayer one tier below BW.
DPS runepriest (not as a sorce of killingblows and main source of damage presure but as a debuffer!)
A debuffing runie with good coordination to his SM partner will be applying so much presure from aoe armor debuffing and 50%incoming healdebuffing on the Bomb-anchor location. This build is heavy cooldown based and does NOT work well without a solid SM for Whispering Winds. This class is close to a must have if you run CriticalMass roam warbands and have 2fullgroups. But the Runie alone will not do the killing, he will set them up for you.
Swordmaster. Some stat value from his Bladebuffs, not to the same level as the Auras from knight. Whispering winds being the main arguement from bringing a SM to a warband group as your selected tank. Group absorb to deny some crits/selfpumps on sorcs is solid. Whispering winds being locked behind the class mechanic is not always as easy as the BO tactic version but is the one of the only tools to deal with the MSH cooldown increaser destro run alot of lately, so the classes is a must have especially for a DPS runiepriest warbandparty.
Healing Runepriest
in a 2-2-2 group if you have a warriorpriest with prayer, and a runepriest with 25%healing on crit tactic, AND a knight with 15%healing tactic. That group is Solid AF in terms of healing. The Runepriest is supplying AP ritual for the party, willpower+ini buff to make everyone tankier, and buffing the warriorpriest to become a God in terms of quick muscle heals while he can move in between heals. The obtion to run flashheals while kiting and repossitioning, armor procs from his hots tics are some of the tools bringing the RP higher on the tier-list than an AM.
B-tier:
Pull engineer.
Highest value corp aoe debuff to set up your kill zone for the BWs. Aoe interrupt a healer stack, landmine on 24 aoe cap is overtuned + tactic to increase builduptime. pulling 6targets is cute for funnels and decent when a fight is already won and you are cleaning up. Conq 5piece bonus procs of abilities like Napalm so thats the easiest and highest value of aoe debuffing ini on order with just one GCD and fire'n'forget. Engineer also has the only none-morale aoe knockdown on Order but as the cost of going melee 1min cooldown and sacrificing his Turretstacks, making him a very stationary DPS role and more of a utility spot you will fill in party4 when your 3 solid core groups are functional and done.
AM healer. Immobile healer, with no good groupbuff compared to his competition from RP/WP. MoM snare + ini debuff pool (doesnt stack with engineer conq proc and lower value) Singletarget Morale pump and the only relyable warband pump available on Order. Instant ress tactic while stunning yourself, a class mechanic that is not suited for largescale all of this makes the healing AM fall behind in raw numbers and value but if you build your warband for kiting AM is a must.
C-tier:
AoE WL.
Pets die in largescale so running without pet is pretty much a given. The available morale pump for this class is tied to the pet, and the M2 drop is on pair with Mara. But this class brings lower aoe presure than a Slayer or BW, has a weaker class mechanic. Only utility you can bring is weapon procs, an M2 drop but no selfpump. WL is just not a warband viable min-max class atm.
DragonGun WH.
Oh boy did I have big plans for this as a cheese to destro running full morale vs perma drained on Order. But due to the 6v6 ballance that hit the Dragongun drain the Value is now way too little on a 10sec cooldown (5sec with WW) But the value of the sheet drain to go toe to toe with 3draining maras is just too little to allow this class a warband slot in min-max warbands atm. You loose too much in not slotting a BW for the damage a slayer for the utility in the case of inviting a Dragongun WH. unfortuneatly! 
Ironebreaker.
A really solid duo tank or smallscale beast. But buffing one target with Oatfriend vs a knight buffing a full party, is just too much lost stats in too little return in buffing a Slayer, unfortuneatly!
IB only really bring aoe snares to a warband arsenal of tools. Unclenseable snare on the AoE punt is cute, but hardly worth a warband spot for that reason alone.
D-Tier:
SW.
As good as ASW is in smallscale this class just doesnt bring ANYTHING to largescale. buffing crit on a tactic, having stronger singletarget burst on lowtargets, ghetto aoe, ap regen buff. Everything is just super meh and outmatched by other classes.
