I think it's time that tanks stop worrying about who's best and we worry about working together to accomplish the goals we have. Regardless of who tanks, lets look at the skills they offer that would benefit any tank and any good member of a raid should be using to make the tanking job successful (i'm speaking regardless of bugs and such that affect these abilities):
Paladins - Grant of Armament, Aegis of Hope, your wards, your heals and LoH - aside from the obvious use of heals and wards, the first two skills will actively provide AC and prevent hits to the main tank.
SKs - Infernal Pact (ward + lifetap buff), Evasive Maneuvers (shield the tank from damage), STR debuffs, etc.
Monks - Mend, Tranquil Blessing (reduce hate on a party member... say your nukers/healers), Martial Discipline, Sacrafice (both protect the tank from damage), plus some debuffs
Bruisers - Overtaking Blows (shields tank), Eye Gouge (decrease target accuracy, thus making tanking easier), bunch of debuffs and offensive buffs
Zerkers - Infuriation (shield party member), Havoc (increase group AC and STR), Offensive debuffs
Guardians - Allay, Never Surrender, Sentinel (all 3 shield the target party member), numerous defensive group defensive buffs, target debuffs (slow/attack reducers)
Regardless of who tanks... combine all this together and THAT's a tank. You may think taking another tank along with you is worthless, but i promise having 2-3 extra tanks around that are of different classes can make a raid easier to tank solely based on these skills. This is not an individual game (especially when speaking about raid content) and the only way we can truly make it easier is if we stop bickering about who's best and start figuring out the best way to achieve our goals. I don't freekin care if guardians are the "best tanks". All i know is if there's one tanking for my raid, i'll be right behind him supporting him with my tank protection/debuff/whatever skills to help him succeed. Likewise, i'd expect him to do the same for me if it were the case that i'd tank. Raids are not a solo effort so we should stop speaking as if tanking a raid is meant to be a solo effort.
-Aeg