The short:
I personally like SK + Inquis but I know a lot of people like SK + defiler or fury. (that is if your tank is an sk). SKs are constantly tapping back health with their own buffs and spells and reactive.
The long, here is my why:
I have 3 accounts now and I can 3 box.
My favorite trio is SK Inquis Dirge.
My original main close to EQ2 launch is my SK Zehl, always my most beloved
. If you enjoy another tank more go for it but it is def the evilest tank, good for soloing IMO and most fun, though sadly SOE doesn't care about them, even though a raiding dev plays one so, they are the weakest tank.
I added in a dirge upon inheriting one at 50 a little after DoF. That was hot, mostly then a dirge's purpose in life was power regen. I was able to do a LOT with the dirge I couldn't do solo, esp when they got a heal and I learned to better work in the debuffs. They both do and debuff disease damage which works nice. But not being a true healer it limits you to easier things you may not be able to solo, and I also heart tracking.
The next duo I tried was a brigand with my SK. That was also a lot of fun, and things died fast with brig on auto attack with poisons, but the brig has nothing to offer as far as buffs. Also, not having a healer hinders you from doing some things.
I created an Inquis to someday grow up to duo with the SK, and then my guild needed one in the raid force and I leveled her up. That was a really great duo, I had fun and was able to do about anything I wanted. I know templars are probably as good or better, but I prefer evils. Things died fast as well with this duo.
A note on pally vs SK for this purpose, pallys can heal themselves but, if they are healing they are not also doing damage at the same time. Everytime an SK is getting life back they are hurting the mob to do it - efficient.
A note on fury + SK: furys have good buffs for an SK, but they don't have reactives or wards, and their heals must be pushed often, which I think makes you need to be too active on both which makes you cut the quality of both toons.
The way I multi box, Inqs (or templars, I did borrow a friend's once and it works as well) work very well with SKs because of the long lasting reactives, I would guess shamens with their big wards would also work very well.
I have fun with my SK & Inquis, but sadly both are classes that SoE cares little for. Inqs used to be amazing but T8 had everyone catch up and pass in dps and healing is VERY much weaker than all other healers if you don't have every piece of overloaded heal gear.
Re: Dual-leveling, which classes to pick?
