My favorite by far is N/W (10 hammer, 9 blood, 7 curse, 4 Soul):
Skills: Mighty Blow | Counter Blow | Flurry | Parasitic Bond | Vampiric Touch | Shadow Strike | Life Siphon | Blood Renewal (swap in Hammer Blow, Well of Blood, Mark of Pain, Suffering, "For Great Justice", and Rez Signet at times).
Look cooler than W/N, mana for days, curses make up for lack of W primary armor penetration, and SR gives you gobs of mana when you get going. I'm also smacking things around for 100+ with my pre-order War Pick so I dun think my melee is hurting at all.
IN Arenas I dominate.
Next is R/M (8 marks, 3 smite, 2 beast, 2 wilderness):
Fairly new to this, but with a 14-25 short bow (1.8s fire rate) customized and runed, I 2-shot most things. Favorite combos in early levels are Ignite Arrows + Dual Shot, and if they're grouped around you drop a Symbol of Wrath + Troll Unguent for instant AE damage while you tank with regen, add the above combo and you won't be getting hit much for long. Plan to get some Expertise skills eventually and spec out of a few things for it.
Finally messing with an E/Me, domination/fire for now.
The E mana is over 50 @ level 7 already, and if I conjure phantasm and alternate my 9-18 wand and Flare with Aura of Restoration on I can pretty much take down any single target very fast and efficiently. But my favorite thing is to run up in melee, aggro as much as possible with Aura on, and do the Lava Font > Firestorm > Lava Font combo, which works much better since the Firestorm patch even. Clears things about as fast as the R/Mo or faster, and heals you pretty good.
Last slot is N/R for now, but I plan to delete it b/c of offensive name before I'm banned and make it my PvP char slot, since I'm now unlocking all 6 classes' skills using the above combos.
* Last slot is now PvP, my N/R got the axe today.