Thanks to Spec Ops, Mercs are highly more Controller-y than Thugs, so like many things in CoX it boils down to your playstyle. Thank goodness there is an actual difference between trained specialists and street trash who know how to hit things... 
/ Would take Mercs over Thugs any day.
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Each have their playstyle i gues.
Mercs as said have a bit more control, they are all ranged (unlike brucer or what is he called) and the medic has stimulance to keep your pets mezz-free.
I would pick merc over thugs anytime, mainly because i really dont like that pee-shooter sound of the first pets and your own gun sound.
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In PvP, thugs pawnz. And mercenaries get over-owned by them. in PvE, it all boils down to your preference.
As others have stated, mercs have the control, but I can tell you now that thugs do mad single target damage and good AoE. Lots of fire damage as well as lethal and smash.
You also get the coolest powers from several AT's under your control like the AR blaster's Ignite or Fire Tanker's Burn patch, you get breath fire and moltovs like the demolitionists. Super-strength's KO-blow is just great!! and you got Foot stomp, hand-clap, jab, punch, haymaker and good resistances on the Bruiser. Not to mention the mad defense buffs from the Enforcers, who also do the coolest animations when firing the Dual Uzi's (especially Explosive Clips. that just rocks) they also carry AK's when not upgraded. And you can't overlook the awesome matrixy trenchcoats.
If you're playing a MM though, (especially with Bruiser) I would strongly advise using GoTo commands. It solves many annoying problems with pet positions and power-combinations (if you know what I mean?)
I've seen them in action, they really can do so many differnt powers 
Does that bruiser still have those 'i stand near a mob but dont attack' problems?
Maybe i just roll one sometimes, i asume /FF or /dark is dah way to go?
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Imo mercs are so dull, i got mine to 43 and i cant even bring myself to log him in any more, not sure if thats down to him being mercs though or just the MM AT.
Id have to say watching people play thugs or robots they do seem more fun and also seem to do alot more damage than mercs as well.
Sinergy: Does that bruiser still have those 'i stand near a mob but dont attack' problems?
I dunno. I send mine headlong into the mob, (GoTo_All) and he usually goes KO-blow > Haymaker > Foot Stomp etc.
Lol, what were they thinking giving a thug a lvl 32 power!?
Elaborate..
He's talking about the Bruiser getting Foot Stomp (9th tier in Super Strength) with the second upgrade (9th tier in Thugs).
[ QUOTE ]
He's talking about the Bruiser getting Foot Stomp (9th tier in Super Strength) with the second upgrade (9th tier in Thugs).
[/ QUOTE ]
if he doesnt like it, then the real question is, "What is he thinking giving the bruiser the lvl 32 power"
you dont have to (damn why isnt there a sarcastic-smile smiley)
[ QUOTE ]
He's talking about the Bruiser getting Foot Stomp (9th tier in Super Strength) with the second upgrade (9th tier in Thugs).
[/ QUOTE ]More sweet AoE damage 
Lol, along with arsonist and empty clips form punks, oh, and let's not forbget the enforcers
My first MM was/is a Merc/poison and I have had good fun with him, even managed some success in pvp.
But now in the age of Thugs I am wondering, are Mercs needed anymore?
Given the choice what would people rather have mercs or thugs?