Prot Paladins have Shield of the Righteous, which does 400% of your AP in holy damage to an enemy. That's equivalent to 1 Templar's Verdict from a Ret paladin, assuming they both have the same AP, since TV is 400% AP in holy damage as well. So is Ret's Blade of Justice, which is a holy power builder with an 10.5 sec cooldown.

Difference is, Prot paladins get 3 free charges instead of having to manage holy power, those charges recharge at a rate of 1 per 16 seconds, there's an optional talent at level 15 that gives you another 3 for free every 3 minutes, and every time I use the ability I get 4.5 seconds of 25% reduced damage from all sources - something Verdict and BoJ don't give.

At level 15, Ret can take a talent to increase Verdict's damage by 20%, but Prot gets the same effect just by standing in Consecrate, which also brings the damage reduction to 30%, and can take a talent at level 30 so that they don't have to be standing in Consecrate to get those benefits. Plus, I can take a talent at 100 where every use of SOTR reduces Avenging Wrath's cooldown by 9 seconds, making it an even stronger ability.

And I haven't even gotten started talking about Avenger's Shield.

I'm ranting, but yeah. Most powerful ability available to Ret is Execution Sentence at a potential 1100% AP damage every 27 seconds, and some of your baseline abilities (Crusader Strike, Blade of Justice) are stronger than Prot's, but Prot's much more reliable than Ret, which tends to hope RNG is in its favor, and even then doesn't shine that much.

Don't get me wrong, I mained a Ret paladin for a long time, but it's unreliable and not nearly as powerful as it should be, whereas Prot has better burst potential and better survivability (as it should, being a tank spec).