At the end of the day, subject to a little variations, a protection warrior’s talent specialization will probably look a little like this: http://mop.wowhead.com/mists-of-pandaria-talent-calculator#wyUi
Our first choice at 15 is between three mobility talents. and I’d recommend Double Time, with Juggernaut following close behind. Of the choices available, Double Time is the one that more closely resembles the flexibility of the old Warbringer talent which made warriors such a mobile tanking choice in any encounter. While Warbringer can potentially be very useful when it comes to charging down a lot of mobs, it’ll have no effect on most bosses which makes it a substandard choice when compared to two talents that will be active no matter what fight you’re part of.
At 30, the obvious choice is Enraged Regeneration. While Second Wind can be useful, you’re likely not going to spend too much time under the 35% hp mark. Impending Victory can be nice but it requires you to have a hittable enemy on hand to activate its heal while Enraged Regeneration can be used at any time and has more healing right then when you need it most.
At 45, it comes down to the utility choices and I’ll have to lean to the tried and true Piercing Howl. While Staggering Shout follows very close behind, if it’s a choice between keeping enemies snared ALL the time or rooted once every forty seconds, I’d have to go with the snare. Disrupting Shout can have its uses but is a very situational ability.
At 60, the choice is between Shockwave and Dragon Roar. I’d recommend Shockwave due to its lower cooldown and longer stun. Though Dragon Roar will potentially stun all around you as opposed to Shockwave’s frontal cone, in the majority of situations, you’re not going to find it hard to get the enemies to shift so that they’re all inside the effect range, effectively making Shockwave perform almost the same as Dragon Roar with a shorter cooldown. There might be some fights where you’ll want that knockback dur to certain mechanics but like Disrupting Shout at 45, those are very situational.
At 75 we have a bit of a hard choice but I’ll give the nod to Safeguard. Mass Spell Reflection can be potentially life-saving but again, very situational. And my issue with Vigilance is the long cooldown compared to Safeguard which does almost the same thing but every 30 seconds instead of every 2 minutes. Also, the Safeguard modification to Intervene also acts as a snare break which can be useful in those tense moments.
Finally, at 90, we have a big damage talent and I’d recommend Storm Bolt for tanking. Avatar CAN be good but as a tank, your damage isn’t really going to compare against your pure damage dealers so you’re mainly going to be blowing it at the start of the fight for that extra threat cushion and maybe during Heroism/Bloodlust if the fight lasts long enough. Bloodbath sounds like it can have a lot of potential but with the inclusion of Piercing Howl into the build, you’d pretty much just get that extra 30% damage as a bleed effect. Storm Bolt has the baked in CC for situations where the mobs are stunnable (and at a range no less) which can definitely save lives and in situations where the target cannot be stunned, the ability does 3 times the damage and is on a shorter cooldown than the other two options.