For pure DPS it is 3x necro. One or two with tank pet, other(s) using a rogue pet. Mix in a wizard for better travel options or an enchanter for better crowd control, slow and mana regen. Of course you can also take NEC+ENC+WIZ if you want all of it. Regarding the mercs use one healer and two melee dps mercs.
3x necro would be a fun ride of an OP wave. 2x mag/enc would be a more conventional choice. mag/enc/dru would probably work too, but I don't think the druid brings enough to the table to be worth it unless you play at a high level and make use of their healing in a significant way. sk/enc/mag could still technically be called a caster group, though it'd be a more conventional group. Could replace the sk with paladin and the mage with a necro.
That's what I played for several years (admittedly, not well), and threw in the towel eventually for a real tank, and now play MAG/SK/DRU (still, admittedly, not well), and it's head-and-shoulders better because of all the additional content I can handle with relative ease. And the main reason there is the total suckage of merc tanks in multi-mob situations. And the SK is doing 3-4 times the DPS of said tank merc, while tanking much better. One of the things to consider when people ask about "best" combos for boxing, is the difficulty/challenge of playing those classes. If the player struggles badly once a certain threshold of difficulty is passed, that combo is no longer "best" for them. A great examle is Tucoh and his all-melee box team, which destroys everything in its path, including current content. So why doesn't everybody play all melee, since it's "best"? Cause it's pretty hard, and only certain people are good at it!
I said it's the best because it is easiest caster group to box. SK is a lot more work to box than a /pet attack, and even using a tank merc, it's best to not be completely merc dependent. MAG/ENC/DRU is the best caster box group because it covers paci, mez, non-merc caster tank, healer, backup healer (mage pet heals), slow, snare, port, track, and so on. SK out tanks mage pet but Cleric out heals druid, still suggest a druid though, because cleric mercs, and etc reasons. Given that I main a ENC, multi mob situations are usually non-existent, and a generally a non-issue when they are. I box a CLR, not a DRU, so maybe the two are more significantly different than I think they are in healing, but I don't see content I can't handle anymore. My tank merc handles just fine, and when it cant, I drop a ROG for a CLR merc. This wasn't true in TBL. Maybe it's because I have more merc AA and raid armor on my boxes now, or maybe it's the tuning differences in the expansions. I think that tank mercs hold up okay though.
It's hard to beat an sk based box team because you can largely use the sk and do OK, popping onto the other boxes infrequently. If you're using enc, mag, dru, unless you're just grinding down blue mobs you'll need to switch between them more frequently.
I just want to play my ENC. The less my boxes distract from paying ENC, the better. Boxes are a necessary burden for many of us.
