Caveats... This is old now. I used to 'box' 6-18 in EQ, but using macroquest2.

The group setup was Warrior, Shaman, Enchanter, Cleric, Mage, Rogue/Monk (Started with a monk, ended up with a rogue, better dps/options.)

A buddy of mine used to have SK, Wizard, Druid, Bard, Cleric, Berzerker. (This was part of the 18 at various times. We shared.)

I would not recommend any melee classes, you will struggle a lot.

It is a completely different thing to use mq2 versus ISBoxer in this context, that should go without saying.

As a Tank, I personally found the warrior to be the best tank. Between the warrior and the SK, the WAR was always the main tank.

EQ is very much a game about CC/handling many mobs at once (in my opinion, at least.)

The SK is by far a better tank for multi-trash situations if you have mediocre CC.

With the Enchanter doing great CC (Which you won't be able to do with ISBoxer.) the Warrior was a superb tank.

Given the difference between ISBoxer and mq2 (mq2 is automation of basically every class other than the tank and we would sometimes 'drive' each others tanks via irc/mq2eqbc on occasion too) You will want:

Paladin/SK tank since CCing in EQ is high-management.
Shaman has really nice group heals/slow.
Cleric really nice single-target heals.
The Necro is a good suggestion, actually, since that's relatively easy to work a rotation for.
Wizard would be a nice one, simple dps.
Mage, same, send pet, spam nukes.

The bard idea, is good in principle, but again, bards are high-management. (/twist is a mq2 command, not a EQ one, btw.)

There is clearly a difference in automation versus 'macroing' as we do in WOW and is more common in this forum, but personally, boxing EQ with mq2 was easier and more effective.

WOW and EQ are very different and doing a full group in EQ with the constraints from ISBoxer/WOW would be difficult to do to the same level of satisfaction. (This in my opinion and to my taste, of course.)