Johanna the Crusader I believe is the strongest tank in Heroes of the Storm as far as survivability and her utility to effect different enemy team compositions

Build #1 - is the main build I go to for tanking, it is well rounded and has many survival worthy talents.
(Focus on W and Passive Effectiveness)

Build #2 - Has a few talents altered to add a little bit of anti-heal and if you can complete the quest on punish, makes it an ability you can spam quite often that slows so heavy that it almost feels like a stun. It does lose a little survivability in the passive CD and Shield but gives great pressure to enemy healers.
(Focus on W and Q as main tools for disruption and survival)

Build #3 - Is less of a tank focus and more of a bruiser but also gains some extra wave clear and allows you to keep enemy team blinded. It will utilize the blinding flash that heals later game as a survivability tool.
(Focus on W and E as primary skill usage, E to Blind/Heal and the W to Increase Lane Presence)

Alternate Choices -
Tier 1 (Divine Fortress) - Only against Hard Hitting Physical Attacks, but has Gambit so is a risky choice.
Tier 2 - Always choose between the attempt to upgrade Punish slow, but for consistent play Hold your Ground is always choice. Eternal Retaliation is only decent when playing a more bruiser role then Tank.
Tier 3 - This is always situational. Sins Exposed is great if you need to combat heavy healer compositions, Conviction is Favorite but it and Steed Charge are both effective at improving utility for tanking.
Tier 4 - Ultimate Choices - Blessed Shield if my team is going for ganks and quick effective kills, but Falling Sword is better in long drawn out fights and can eventually even add a little healing.
Tier 5 - Almost always I choose between Holy Fury or Blessed Hammer, no matter what style of build you usually want to still be effective tank and putting to much focus into the Q weakens her tankability. Holy Fury for a more passive effect and Blessed Hammer for doing extra damage but also forces me to use the skill manually and to Auto-Attack more often to help restore cooldown.
Tier 6 - All these talents are good in my opinion just depends on the build that you have been going and how you want to tank for the rest of the game. Holy Renewal is great blind that also gives a burst of healing depending on enemies hit. Blessed Momentum is great if you are trying to focus on Slow/Anti-Heal/Auto-Attack builds. Shrinking Vacuum is a powerful anti-damage debuff that is usually hitting the main damage dealers
Tier 7 - The only choice is usually either the Healing Upgrade to Falling Sword or Blinded by Light Shield or an Extra Shield Passive. The Upgrade to Blessed Shield is not very strong but is effective with gank compisitions