So far some theory crafting has shown that with BiS ICC gear shadowmourne gives the most theoretical dps to a ret paladin.
And instead of speaking drivel and not backing it up ill explain why.
1. Passive armor pen cap for DK's and warriors without the weapon. with BiS gear and trinkets.
2. Damage modifiers for The proc. Ret paladins have 18% damage modifier at all times.
3. Scalability. Yes we only get 15% strength vs 20% warriors but... we also get 30% SP from attack power. Pushing everyone point of strength well beyond the benefit a warrior gets.
4. Charge building. A Ret paladin will attack more times per minute with physical attack using Shadowmourne then any other class therefore building charges faster. This is of course using 2p T10.
5. Dk's and warriors do excel at "Cleave fights" However, single target dps A ret paladin still wins. I have personally pulled 11k on Twins with trivial cleave damage. While the warrior did 12k almost 35% of it as cleave. This can not be looked over because there are many single target fights in ICC.
6. Weapon speed scaling- 3.7. Its true that all classes benefit greatly from this but here again is where ret double dips. Seals are not normalized like instant attacks therefore benefit 100% from weapon speed. That means are seal damage scales much higher than any other class with a slower weapon. Also with the way ret benefits from haste we will see the attack speed go down to 2.3-2.5 based on gear.
I am a ret paladin. I am the GM of the guild. I also push top dps against single targets. The only people that compete with me are arcane mages and yes you hear it here first. A ret paladin will be getting shadowmourne.