ench/cler!

Ranger/Ranger is clearly the best. One to get the hell beat out of them and one to bow kite the mob while the other comes back and gets his gear and then begins to make arrows so he can bow kite once the other ranger runs out.
After that mob dies/they zone they can complain about how Wurmslayer is primary only now and their 40% exp penalty is why no one groups with them. The best part, is they can both reassure each other that the penalty is why people aren't grouping with them while embracing in wood elf love.

Mage / Wiz

Hate to break it to you, but Mage/Wiz is actually a rather poor combo. I'm not saying you can't grind with it or level effectively together - but there are no real force multipliers or complimentary skills between the classes except wizard root and stuns. Remember that any duo can buy ports - so choosing a duo partner based on their travel ability isn't as effective. You have to focus on what they can actually do in terms of grinding, camping, etc.

Mage/Mage is far superior to Wizard/Mage in that regard, since they can use pets that compliment each other. For example - backstabbing water pet and earth pet. With proper pet commands, positioning is rather easy to make sure the earth always has aggro.

And since a wizard has to med so much without C2, you could just have another mage and just summon a useless 50+ fire pet to spam nukes. They'd probably top the wizard's long-term damage over the course of a grind session - and obviously an air/water vocarate pet would be superior to that.

I've tried ench/necro and it's really awesome even at earlier levels. Bard/monk is very fun and efficient too. And Bard/shaman if you want to kill mobs slowly but be at infinite hp/mana the whole time :p

shaman/anything

Bard/wiz.

Take a second and think about it.

Any two pet classes.

(See what I did there?)

yeah wiz/mag doesn't seem like it would be great and mag mag would be better but it still is an efficient combo at higher levels. Watching a earth or fire pet tank the mob to 50 percent or so and then having the mag and wizard cast there nukes can burn down mobs EASILY. The mage having malosi helps out the wizard as well. Yeah your gunna have some down time to med of course but they really can take a mob down easily before any other class combo imo unless its a high MR mob tho.