The Spirit Realm

Id go with ranger, Get him a few more upgrades and get his hps around 10k(buffed) and he can tank easily in WoS, before my ranger friend xferd i 2boxd him in WoS in the early hours and snagged all the named that pop'd up and gave runes to our alts and friends. He was a little better geared than your ranger(1.5, 11khp, 400aa 1900ac buffed) but with the right defensive aa on ur ranger it'd be np, dps all the way. If your uncomfortable with ranger tank go for the sk, and pump out the dps on shaman(panther,champ, dots, pet).

Well, I can't speak for many of these classes, but I do have to comment on the necro/shammy combo. This is my current boxed set (58 sham/69 nec), and I love it. First, the good stuff. With this combo, you can take down anything that doesn't summon.... period. That's a given with the necro, and it only gets better. As to pet tanking, it's very possible, but you're going to have to hold off a little on the shammy dps, as pet taunt is not all it could be. The nec can DOT his heart out and dump agro with FD aa before the server tick hits and he gets summoned. The cool part is that the 67 nec pet regens like crazy when not engaged - functionally as long you heal the pet just enough for him to survive the fight, he'll be full or nearly so by the time the next mob is pulled to camp. I hear this only gets more disgusting with a pet focus; I don't have one yet.

This is more than good enough for POP+ mobs. The bad news is that for WOS+ mobs, the pet is more or less paper. He has 6k hp + buffs and no gear/no aas. So start out with the expectation that the shammy will be tanking the harder stuff. That's ok though - for the stuff you need to kill (duoing named mobs for instance), the equation for shammies has always been: Can I do enough dps to kill this before I run out of mana while still keeping myself alive? In a nec/shammy combo this gets much easier - the shammy will have agro easily with debuffs/heals/nec fds and won't have to spend any mana on dps, thus being able to last longer. The necro can dps for the team without being squished as usual - normally the problem is that necs have to lifetap back each and every summon at abysmal mana ratios - with someone else to take the hits the nec can use much more efficent dots (some have a mana to damage point ratio of over 7 even without aas) and will have the added bonus of keeping a pet around (the pet usually drops a few seconds after you FD, dropping our sustained dps fairly significantly). In a normal xp group (WOS+ grind sessions) you realy only need a tank along - a cleric or druid is nice to have to take the heal strain off the shammy and add further sick dps, but not necessary.

Look at it from this perspective - what types of abilities are generally used in a group?

Pulling - Shammy via Virulent Paralysis, Necro via pet pulling or snare split (in content without terribly high resists, I often don't bother traditionally splitting the mobs if it's a pair - just start a cast of root on the nec at the same time I start casting slow on the shammy)
Buffs - Shammy - nuff said
Healing - Shammy hots and dd heals, Nec via orbs, group taps, or hp transfer (note that with a demi-lich skullcap, a nec can be sending your shammy 125 hp/tick for canni use essentially for free)
Tanking - Nec pet or shammy
DPS - Nec and shammy both decent dpsers
CC - Shammy via root, nec via root, snare, lower level mez, kiting, or aborting the pull via FD
Mana - Shammy and nec can each take care of their own mana, nec can pump or MW (Pumping the shammy while buffing up the group helps downtime and makes the nec much more useful at startup)

The bottom line is this - some mobs are going to require a group no matter what you do. For the uber mobs in the game that are soloable, most are soloable by either a shammy or a nec, not too many other classes except in specialized cases (unslowable mobs being eaten by a cleric's reverse DS like the recent Vindi kill or a druid using a greenie swarm to proc self-heals). Together they're unstopable. Just my perspective, but out of all the combos available, this will be the most flexible and powerful set.

Lets not forget self sufficency, Shaman and nec are by far the two most self sufficent clases.

For grinding out AA's (and leveling my alts), I generally 5 box the following combination:

70 Shaman (me)
66 Paladin (full defensive AA's for his level and now working on levels)
70 Cleric
66 Ranger
67 Enchanter

Maybe not the best combination but it works for me - I have all the required skills covered: Healing (in abundance), Slow, Snare, Damage Shield (Ranger and Cleric) Pacification, DPS (Ranger and Shaman DoTs); ability to hold aggro (Paladin Stuns). When my wife plays her druid with me I also have a porter/evac person.

Works for me,

Jind