My thoughts from Threatening and soloing.
Biower Plz OP Nerf Tier:
Legionnaire - the best tank period. Potentially unkillable, but not everyone likes anti-DPS play style.
Elementalist - not squishy at all, big nukes, great CC.
Alchemist - played well is amazing, just has a higher requirement for positioning and timing than other DPS kits.
Archer - simple DPS. Boring but effective* (excluding PUG archers).
Arcane Warrior - best adaptability: melee, CC, ranged. Not the best at any of those, but love the flow of swapping at will.
Necromancer - not played, but they seem very good. Again not squishy at all, and make great aggro pullers.
Keeper - like Lego, sort of the straight boring one in their class. Played well a huge asset to team.
Useless, need moar buff Tier:
Katari - unlike AW, being in the middle dosent work. Not tanky enough, not DPSy enough. They seem to die a lot...
Hunter - another middling-didn't-work kit.
Templar - another middling-didn't-work kit* (except vs demons).
Assassin - quite effective, but between stealth, aggro and archer issues, seems harder work than other kits.
Br0ken, need fix Tier:
Reaver - should be in Biower plz nerf tier, but Rampage-Fail leads to unfortunate deaths far too often.
It's all kinda easy mode right now (ignoring bosses) , but some kits are just that bit trickier to do well with. Personally i'm of the opinion that unless everyone is using one particular thing (so it's outright non-optimal to use any other choice) then that thing is not over-powered: it's just really good.
In DAMP the "thing" that is edging to being overly good is healing: so health-on-kill; health rings; kits which side-step healing. It seems like other choices are slightly less optimal. This may change as we unlock more items, and at the moment other choices are viable, so it's wait 'n see really.
The problem with team synergy classes is that another more self-reliant class can often do similar things and still be effective should things go wrong. Lightning Cage on a Keeper is a great example as it weakens the Keeper just to make the Katari better. With an 8s duration and a 32s cooldown for 65 mana, casting Lightning Cage severely handicaps the Keeper despite providing some crowd control.
Ideally weakening oneself should provide enough benefit to make it worthwhile. So yes the Keeper could sit there pew-peeing and casting barrier, but a cage+katari combo should be "oh my deity(s) everything just died" moment.
Broadly i do agree though, i'm enjoying kits more which can operate independently of the team if needed. Especially if you can side-step the "no-healing" thing i.e.: Reaver, Elementalist, Arcane Warrior i all very much like. It's not an OP lone-wolfing thing, just they allow a greater variety of options irrespective of the PUGs kits.
Bioware need to make team synergy more attractive, because at the moment i'd rather have the adaptability.