orc 2hander is very deadly, i used one with a battleaxe for a long time, got ambushed by two dragons, popped his power and killed them both in 30 seconds. ridiculously powerful.
breton deathknight would be very powerful too especially if you thralled summoners. wouldnt need to be as tanky kill speed is more reliable, though maybe not as fast as when the orc has his power on, but overall i think it would be faster. could also equip the thralls with healing staves too. keep you alive more reliably.
if i understand right basically an evil paladin, but uses things the paladin is sworn against, like necromancy.
Bound Weapons train Conjuration, and cost reduction Perks can make almost any Conjuration Spell cost less than 100 Magicka to cast. Make an Orc Dual Wielding Death Knight.
omg the horror.... those poor ancient dragons.....
From a pure power standpoint dual wield damage is far, far better than 2hander. They have better perks and benefit more from enchants since you get twice as many. 2h has better range and in some ways mobility, but I still find it an awkward playstyle. It does have a bashing option that can be significant with some block perks though, and deals better power bash damage than a shield even IIRC. That won't make much difference on legendary but on adept or expert maybe it'd be a selling point. Power attacks with 2handers are quite awkward at times though, with your character lurching forward performing a fairly slow attack. However, dual wield has its own issues since you can move while making a dual attack or power attack.
Health/Magicka/Stamina levels depend on what you're allowing yourself to cheese and what difficulty you're on. Stamina can become pretty much ignorable if you're willing to use absord stamina or vegetable soup. On Master or Legendary it's also better to stack health to survive any form of heavy burst damage.
I recommend light armor if you want to use natural/less cheesy stamina regaining options, for the 50% regen perk.
Personally I've never gone above the base 100 stamina on any character and I see no good reason to unless you want to gimp yourself and ignore superior stamina managing optons. Even respite in restoration can make up for it to a decent degree, though it does require sheathing a weapon or shield.
Death knight definately
http://theskyrimblog.ning.com/group/character-building/forum/topics/character-build-dark-knight