Controller is in my opinion the most difficult class to generalize about because each combo produces very different types of characters.
I've been meaning to do a write up like this anyway, so here are my thoughts:
ILLUSION
Only available on Controllers
Best things
Unkillable pets that do good damage and can tank AVs/GMs
Worst things
No AoE hard Controls at all. Very different from other Control sets.
FIRE
Controllers
Best things
Passive damage aura (Hot Feet) that benefits from Containment damage. This makes Fire Control potentially very high damage while allowing the character to manage a busy secondary set (eg Kinetics)
Very squishy pets benefit from buffing
This set tends to draw a lot of aggro, so having extra healing/defense etc from a buff set can extend survivability
Worst things
Other than Bonfire, all Control powers are Holds and Stuns, making it extremely vulnerable to lockouts when enemies have Dispersion Bubble powers
Most secondaries offer no mezz protection, making Hot Feet vulnerable to detoggle until you plug this hole
Dominator
Best things
Turning Flashfire into a Mag 6 stun makes it one of the strongest, (if not THE strongest) ranged hard mezzes in the game, and bypasses most of the concerns about Dispersion Bubble above
Since the secondary effect of Fire is just "more damage" and Doms have higher damage than Controller, the values translate better
Mezz protection in Domination mode helps prevent Hot Feet detoggles
Worst things
No way other than Controls to support very squishy pets
Dominator generally has poor self heals/defense to facilitate surviving the aggro Hot Feet can draw
EARTH
Controllers
Best things
Already solid pet becomes nearly unkillable with the right secondary pairings.
This powerset has strong enough controls that going Dominator may not be required to still achieve lockdown, especially depending on the secondary set that is selected.
Worst things
This is a very low damage control set.
Dominators
Best things
The low damage of Earth Control pairs excellently with the high damage of Assault secondaries
Although -Defense scales between Controller and Dominator, it mostly does not matter. The only other secondary effect Earth Control has(-ToHit in Earthquake) is the same (-10%) between both archetypes
Stalagmites as a Mag 6 AoE stun vies for the position of best ranged control power in the game, beat only by Flashfire because stalagmites requires you to be on the ground
Worst things
AoE hold power does not benefit from Domination
ICE
Controllers
Best things
Controllers do more -Recharge as a secondary effect than Dominators do
Already solid pet becomes nearly unkillable with the right secondary pairings
Worst things
This is a very low damage control set that struggles to solo on its own and contributes limited damage to the team
Arctic Air is vulnerable to detoggling until you obtain some form of mezz protection
Dominators
Best things
The low damage of Ice Control pairs excellently with the high damage of Assault secondaries
Mezz protection in Domination prevents Arctic Air from detoggling
The pet is fairly solid and doesn't require much additional support
Worst things
Arctic Air does not increase magnitude when in Domination mode
ELECTRIC
Controllers
Best things
You get the same strength from Static Field and almost the same strength from Synpatic Overload (barring first target) as a Dominator anyway since those powers dont benefit
Pets are relatively squishy and do well with some extra support
Worst things
This is a fairly low damage control set
Dominators
Best things
Low damage in the primary lends itself well to pairing with the high damage Assault secondaries
Unlike other secondary effects, -Recovery and -Endurance do not scale between Controller and Dominator, so both do identical endurance draining
Worst things
Synaptic Overload only applies the Domination effect to the first target in the chain
Static Field does not apply the Domination effect
No real way to support the squishy pets
MIND
Controllers
Best things
Umm... theme?
Worst things
AoE Containment is difficult to achieve, making this set very low damage
Having no pet really hurts most Controllers
Relies on relatively low magnitude, long recharge powers
Few opportunities for damage proc to close damage gap with Dominator
Other than theme, overall just worse than a similar Dark or Illusion Controller
Dominators
Best things
Unlike a Controller, does not rely on Containment for extra damage
ALL powers benefit from extra Magnitude in Domination mode
Mind has no secondary effect, so there is no scaling between archetypes
Worst things
Despite being better on Dominators, the set overall still suffers from punitive recharge times and has no secondary effect to back itself up
DARK
Controllers
Best things
Controllers have higher -ToHit as a secondary effect. The ToHit in Dark Control makes the actual mezzes less critical as enemies can't hit you anyway.
Lots of opportunities for damage procs to help close the hole on damage
Worst things
Only that Dark Control is mediocre damage even with procs
Dominators
Best things
All powers you would expect to benefit from Domination mode do so, even the AoE Hold
Excellent pet requires little supervision
Assault sets assist Dark's mediocre damage
Worst things
Worse -ToHit than a similar Controller
GRAVITY
Controllers
Best things
Very high damage blast types powers that give this set significantly higher single target damage than other control sets, obviating the need for an Assault set
Worst things
All Control powers are Holds or Stuns, so vulnerable to lockouts when enemies have Dispersion Bubble powers
Dominator
Best things
Wormhole in Domination mode is the best ranged hard mezz in the game (a mag 6 non-notify stun with a teleport effect) so it may be worth playing this combo just for this.
Though the secondary effect -RunSpeed scales across ATs, it probably doesn't matter
Worst things
Relatively few powers benefit from Domination
"Impact" damage mechanic doesn't apply to Assault sets, so you would be doing high damage even without an Assault set
Extra damage mechanics in some other Assault sets don't apply to Gravity's high damage powers
However might still work well paired with one of the more utility-based Assault secondaries if most blast powers are skipped
PLANT
Controllers
Best things
Does decent (not great, initially) damage on its own
Seeds of Confusion can slot Coercive Persuasion: Chance for Contagious Confusion, which has a very high chance to proc. If it does, the Seeds of Confusion is not remarkably different in Controller v Dom versions.
Worst things
No secondary effect.
Dominators
Best things
Pairs "just right" with Assault secondaries as most of the sources of its high damage capability do not replace effects in the secondaries
No secondary effect means no scaling between ATs.
Worst things
Nearly all of the control capability comes from just one power, Seeds of Confusion, a Mag 6 (in Domination) Confuse. If that misses, Plant Dominators have no buff set to back themselves up with and have to hope their AoE hold is up, run away, or tank through the damage.