I will just note the most overpowered and concerning specs at the moment, because some of them making competitive arena gameplay a complete joke.
DPS:
BM hunter:
Can’t die
Does same damage regardless if focused or not
Pets keep you perma dead
Your healer can’t play the game
Killing pet doesn’t matter anymore
Enhancement Shaman:
Way too much offhealing
Completely broken burst damage
Too much utility
Sub rogue:
Can’t die
Guarantee kills you in a go 100-0 (oftentimes through any defensives that are less than 40% dmg reduction)
Runs away like a clown all game and gets away with it
Demo Warlock:
Can’t die and has WAY too much HP compared to every other class (this applies to every warlock spec)
Does same damage regardless if focused or not
Controls your whole team with CC
Turns your match into an m+ dungeon
Spams crit curse on you so you can’t do dmg
Destruction Warlock:
Too much HP
Too much instant damage compared to casted damage
Must be focused down or your team dies
Fire mage:
Way too much CC
Passive ignite dmg
Hard to kill
That’s it for DPS. Everything else is counterable
Healers:
Disc priest:
Way too easy to play (spams 4 buttons to heal)
Infinite defensives
Very hard to run out of mana
Broken shield values
Refuses to die no matter what if focused for long periods of time
Can even do dmg?
Caster Mistweaver:
Infinite mana pool (especially with 2 set)
Revival immunes your whole team, dispels your whole team and heals entire team for 200-250k on 90s CD and USABLE IN STUNS
Life Cocoon is literally Divine Shield when played with stacking cocoon % talent (over 1 mil absorb)
Hard to kill
Only weakness is being susceptible to CC or kicks, which isn’t a problem if you’re good enough
Honorable mentions: Shadow priest, Warrior, Feral druid, Moonkin, Resto shaman