I haven't parsed lately, but DPS mercs weren't doing much more than 40K ish damage as I recall. The top DPS right now is berserkers. You can basically gear up a melee toon from Bazaar gear and have them putting out serious damage almost immediately.
It's not like the old days when gearing up a tank or melee was such a chore. My mage gets 100K plus sustained DPS, probably more. But his mana goes fast.
My wizards were getting 120K to 140K sustained. My zerker is getting more. A significant amount more.
A well-geared, well-played rogue can challenge a zerker. There is a train of thought that goes get three zerkers and their DPS with alliance will kill mobs too fast for healing.
I think SK, Cleric (Shaman), Bard, Zerker, Zerker, Zerker for example is a very high DPS group. With gear and AAs at 110, you'll be putting out a million DPS.
But the current expansion also requires a ton of healing. Even a cleric against certain progression challenges isn't going to keep up a non-raid tank.
I run a Warrior, Cleric, Shaman, (Bard/Enchanter), Mage, and zerker. I can easily box three of trials. I can kill named in Ash, but my DPS with this group is a bit low for certain events.
But to your specific question, with enchanter, I'd think about three wizards (for alliance) or two wizards and a mage. Enchanter helps mana based DPS more than melee.
Bard isn't necessary, but turns zerkers into buzz saws where I get twice the DPS of a wizard generally.
To answer your specific question, two wizards or two berserkers or a wizard and zerker or even a rogue. Any combination of those three classes will more than double the DPS you put out with mercs.
