my take on the best tank in the game...at least spelldamagewise

race-breton

weapons-1h and shield (which 1h you choose is up to you, i use either sword or mace)

skills

heavy armor, alteration, block, 1hand, enchanting/smithing (not powering them, just level them as i go), pick pocket up to 100 pounds carry weight (if i can manage), maybe restoration. anything else is leveled on its own

guardian stone, either steed (for more carry weight and freeing up some heavy armor perk slots) or the one (forget name) that increases magic resist by 25% and physical resist by 50 points (its a tank build afterall)

best at-tanking damage, especially from magic users

most trouble with-getting dragons to friggin land!

Breton Atronach speccing into alteration and block recives:

80% chance to absorb effects (even shouts and traps), 30 being from alteration, increased to 100% by the racial once a day.

80% resistance straight magicka.

50% resistance to elemental damgage whilst blocking.

Remaining skills should be heavy armor and one handed. Spec into whatever else you want, this build is so cookie cutter and easy that crafting proffessions aren't even needed unless you play on master. This requires 100 alteration but even forgoing that skill you have 50% absorb chance, once a day boosting to 100%, 50% restistance to magicka and the ability to block 50% of elemental damage.

So many people mention taking the pickpocketing perks for 100 extra carry...It's definitely worth it, but do you know how many pockets you'll have to pick to get your skill that high? Or how much cash you'd have to spend at a trainer? I rarely bother to pick pockets even on a stealthy char. With this sword and board heavy armored char, you'll be level 40 and look at your skills just to notice pickpocketing is <30.