I've been messing around on quiet a few classes consisting of,
-Rsham
-Disc
-Spriest
-Feral
-Warrior
-Rogue
-Mage
-Warlock
*I mainly only que scrims/wargames and try to leave BGS to a minimum"
Rsham:
Imo, The strongest healer so far - Great utility to counter practically any class in arenas/wsg. I think shamans are truly
#1 due to how lack luster other healers/classes seem to be with how gimped the CC aspect is.
Disc:
Great healer as long as you dont VS a shaman of any kind - Very few defensive's and mechanics to peel themselves, Guise is good but very easy to get caught out with any AOE/Daze from any respectable player. Priests losing their CC imo knocks them out of the meta comp as far as arena healers go.
Spriest:
Very OP currently - The 3 orb glyph eliminate spriests need for ramp up to have pressure right at the start of a fight. Their off-heals are pretty overwhelming and even more so when paired with guise and PWS.
Feral:
Great melee class - High burst but very fragile to set it up, Feral offheals revolve around procs via spending their combo points. To ruin a ferals rotation you have to burst them right when they open to pressure them into wasting points for RNG procs for their heals instead of building up the generic 2-3 point roar into a 5 point tigers fury FB. Highest burst potential i've seen so far with FB critting over 2.5k on players in arena.
Warrior:
Pretty gimped imo - The loss of slam was a big change and made the warriors rotation feel pretty goofy to me, It currently feels like you spread rend to everything and build up rage to dump on whichever target starts to drop fastest to rend ticks. Kiting and letting rend do the work is a pretty effective method to win 1v1/2s.
Rogue:
Very versatile class still - Sap,gouge and kick being their CC, Not the burstiest melee but their cc makes up for it, Have to be an effective player to work around the rogues CC moreso and not relying on the healer (pre 6.0 arenas where priests/others would be reliant on CC as a rogue just gets 5 point re stealth ambush evis)
Mage:
Class feels really shitty atm, its CC just cant make up for the fact its damage is practically below par a healers DPS - It's even worse when the mage gets trained.
Warlock:
I've only played around as Demo so far so i cant give input on the chaos bolt 420quickscope spec destro but demo seems like a no brainer - first 3 globals in a fight: Metamorph -> Chaos Wave -> Chaos Wave. Probably one of the most viable casters imo due to fears utility, has decent defencives with healthstone + dark regen.
Imo some great arena comps are
Warrior/Restoshaman - You just train healers with kicks.
Spriest/Brewmaster - I havent personally played a BM but their offheals seem pretty present in ability to change games and save lives, That being said - BM peels melee off the spriest, Spriest saves guise for the BM cant peel/offheal - Dump 3 orb into kegsmash and win.
Rogue/Spriest - Rogue saps 1 target in the opener and you kill the other in the sap with ambush 3 orb - Rogue pillars and priest bubbles for easy restealth with dots, very slippery comp easy to reset fights vs practically anyone.
*I feel as if Hpalas would be really good although i've yet to come across any - Also panda is a serious race consideration in terms of CC and utility, It DRs with poly but with how unrepresented mages are I doubt that will be an issue.*