Before anything i ask for patience due english not being my mother language, so forgive me for some errors.

Tanking was always my favorite role since D&D times and in every single game it was my preferred role, but i loved so much tanking at ESO that i decided to right this to explain and discuss something with my fellow players and dedicated tankers. Hope you help me and enjoy.

1 -Tanking at Eso.

In my experience here some things became obvious as i was progressing into the game. As a tank you won't need to keep agrro for more than 2 mobs top, and sometimes even be limited to a single high damage boss. This is because AoE taunts do not exist, and casting puncture a lot of times will mean all your stamina for blocking, interrupt and dodge will be spent trying to keep all mobs on you, that's maybe work on low level dungeons, but in later game interrupt enemy skills and blocking power attacks will be paramount if you want to dish the most dmg possible and keep your group alive. Think the bash feature as interrupt + stun skills there are standard on other MMOS.
So if you got hold on those 2 mechanics in the game you already know how to play a tanker properly, and keep in mind that in Eso any fight is a group overall effort and not about only dedicated roles. I say this because every DPS class build, due the lack of CD, can use just 2 damage skills instead of keeping a rotation, so the more balanced build would be 2 damage skills (single target/aoe) 2 utility skills ( CC/Hide/debuff/purge) and a healing skill, yes a healing skill can save lives and help the healer conserve his magicka for when is truly needed.

2- Picking your Race

I keep saying that any race is ok to tank, but if you like to optimize everything, and many people have that mindset because this will be a competitive pvp game or even because some like to be the best. So let's break by factions.

The Dominion:

This is a tough pick, none of the races have a optimal tank traits, so picking any of those would do the job.

Altmer have a good synergy with Dragon Knight fire skills since elemental talent would increase the damage done by fire skills. has a better survival because his magicka regeneration and extra magicka, so will be able to cast more defensive skills.

Kajith only have robust ( +15% health regeneration) and that's the only defensive/survival of the three.

Bosmer for the extra stamina for taunt and blocking.

The Covenant

Now this is the place of the tanks, and believe me is kinda hard to choose a good tanker here. Orcs have brawny (+6% stamina and health) robust (+15% health regeneration) and Swift (-12% running speed and - 6% stamina as running) and also heavy armor expertise and that would make him the race with the most hp of the game and a good amount of stamina.
Redguard is the master of taunting,interrupt and blocking since all his race passives involves stamina regeneration , larger stamina poll and increased experience with sword + shield. (Vigor+Conditioning + Adrenaline rush + Shield affinity)

Breton: The least tankish race of this alliance, but it's optimal for some builds for the same reasons as the Altmer and because it got spell resistance.

The Pact

Argonian: 6% more healing received, 15% potion effectiveness and 3% more health gives the lizard folk a bit more of survival.
Dunmer : Well rounded around mag and stam, but it lacks any defensive passives, still for same reasons of breton, altmer and redguard he can be a good tanker even more if is a Dragon Knight.
Nord: 3 % more hp, More armor and 15% health regeneration.
Any of those would make a nice tank.

THE INDEPENDENT

Here lies the most balanced tank of the game, the imperial race have Tough (gives 12% hp) which is the largest hp passive of the game, also gives conditioning (10% stamina) has shield affinity and red diamond (10% of gaining hp per strike) make this class the most balanced for the classical aspect of tanking.

3 - GEAR

Weapon : Sword and shield has the only taunt and a lot of passives revolving around block and interrupt.

Heavy armor: Lot's of damage prevention, health regeneration
Forget the idea of the cloth tank, medium armor tank, it does not work well in the end. And about "let's put several pieces of other armor for having more of option" if you scatter the bonus points you will be more balanced for solo play, and even i have some doubt's about that, but will be gimped on the other aspects since the bonus you will have is for piece of gear.

About the overcharge it's limits are increase by level and that's it, if you have reached the maximum value of any stat at next level it will increase, so dividing the armor passives will only make you less and less close to the cap, and even overcharge has your vantages.

Picking you Class

Any class can indeed tank, and that would solely depends of the build you create. In the other betas i had the opinion that the only class that is not suited for taking is NB and after his Beta, this one i made a NB tanker to confirm my assumptions,i was proven wrong.

Templar

Thematic: Paladin

Pros: Can tank while casting group heals, making the life of the healer somewhat easier. Have some nice damage returning skills, useful for both pvp and pve. Can grant itself and the party a large amount of health and stamina regeneration, so it will make blocking and interrupt more of a easy job. Can also heave an stable magicka poll, due the restoring spirit passive, and Sun shield as a damage prevention skill.

Cons:, The only damage prevention skill has a low duration and prevents any mag regeneration for its duration, lack's any effective CC such as roots or snares, his mag will be soon depleted if not carefully handled.

Recommend skills : Backlash, rushed ceremony, Sun shield, Shield charge, Shield bash, Eclipse, Puncture and any other healing

Ultimate: Nova, Rite of passage

Optimal skills : Blinding Light, Puncture, Rune Focus

Optimal Races: Altmer, Breton, Argonian.

Outside skills : Circle of protection, Equilibrium, Bone Armor.

Smart Tactics - Using Sun Shield while in low health and after activating rite of passage inside the Rune Focus or after using equilibrium some times to recover lost magicka

Smart Tactics 2 - Rush to a group using shield charge while backlash, Sun shield and eclipse are active just let them focus you, if you survive for 6 seconds many of them will end up dead and you can use nova to negate their damage and give a massive snare.

Recommended for : Players who like holy tankers and a lot of retribution mechanics

Difficulty: 3/5

Dragon Knight

Theme: Dragon Knight =P.

Pros: All the necessary skills are in a single tree named draconic power. Have the least probability to mess up your build, have a good balance of health regeneration, armor buffs, CCs, mitigation and self heal. A really balanced and easy to play tank recommended for newcomers or players seeking the most traditional tanker.

Cons: Lacks some specialized focus or complex tactics

Recommended Skills: Dark Talons, Reflective Scales, Obsidian Shield, Spiked Armor, Fiery Grip, Shield Bash, Petrity, Inhale

Ultimate: Dragon Standard

Optimal Skills: Ash cloud , Puncture, Dragon Blood. Shield Bash

Optimal Races: Imperial, Orc, Nord, Khajit, Redguard

Outside skills: Bone armor.

Smart tactics: Pull their healers or anything ranged close to your group from walls with fiery grip

Smart tatics 2: Abuse reflective scales when being targeted by ranged players.

Difficulty: 1/5

Sorcerer

Theme : Arcane Knight

Pros: Have the largest potential for armor/spell resisyt of the game, easily reaching the overcharged status, can silence entire groups and remove any area skills, a good call to turn the tide of a battle, passives also gives 4% of hp per enemy hit by a dark magic skill, have 20% passive regeneration, large amount of CC and stable magicka due % bonus and cost deduction, can scape thick situations by using escape bolt on the alternate weapon

Cons: Spells are expensive, Cannot use Dark exchange to restore magicka or health, since will take the stamina necessary to block and puncture, does not have any powerful self healing skill. Not many health and tanking passives.

Recommended skills: Bolt escape, Bound armor, Conjured Ward, Shield charge, Shield Bash,

Ultimate: Negate Magic or Summon storm atronach;

Optimal Skills : Puncture, Encase, Lightning Form.

Outside Skills: Circle of Protection

Optimal Races : Altmer, Breton.

Smart tactics : Bolt escape to a middle of a group, use the ultimate negate magic for an AOE silence and dispel everything, encase their ranged fighters and bolt out while your team advances.

Recommended for players: Those who loves a really strategic class with great potential of survival and initiation, players who love high overcharged stats.

Difficulty: 4/5

Nightblade

Theme: Vampire knight.

Pros: The abusive amount of drain and heals makes this class worthy of the title of this theme, while you attack all your resources keep being constantly regenerated, having also a nice amount of debuffing mechanics, such as removing enemies attack speed, moving speed and passives that also grant an increased amount of hp and mana, also a modified version of power drain gives a fast and reliable self heal. Have the most powerful single target disable.

Cons: Lack of armor buffs, damage mitigation , lacks group CCs. Most powerful tanking skill too deep on the trees, not that much useful ultimates, 15% dodge is virtually useless as a mitigation skill.

Recommeded skills: Aspect of terror, Cripple, Haste, path of darkness, Shield charge, Shield Bash, Defensive posture, Agony, Bone Armor.

Ultimate: Soul shred , Consuming Darkness

Optimal skills : Siphoning strikes, Strife, Aura of Protection, Drain Power

Optimal races: Imperial, Redguard, Orc, Argonian

Recommeded for : Really experienced players, people that like vampires and have a good amount of patience.

Smart tactics: Didn't have the time to play on pvp.

Difficulty 5/5

Extra comments

Some of the skills of each class can mach the same skill in another one. As a example Templar sun shield prevents 30% dmg while dragon knight dragon blood heals for 30% damage, also Sorcerer can stack so much armor and damage prevention that the healer will have an easy time healing, while morphed drain power from nightblade, wich gives him % of health per enemy hit, also function as something close to dragon blood.
In the end the 3 classes end up balancing itself.