In T4 and early T5, LOKI's primary tank was Ruffianx, our legendary guild leader, and Feral Druid. He was the first feral druid to MT several bosses on our server (Darkspear), and cultivated my respect for Ferals as a primary tank. I was coming from the pre-BC standpoint of Druids being cornered into lolHealing and Innervating Priests.
Somewhere in T5, Tanking changed in LOKI. I was promoted into Tanking Officer, and began to MT some bosses, followed by some additional protection warriors. That freed up ferals to do more DPSing on single tank bosses. Morogrim's adds convinced us to get a full time Protection Paladin, though I admit that I only (under-) utilized them for trash and adds, and reserved bosses for the protection warriors and Feral Druids of the guild.
Vashj was killed with a Warrior MT (two of us did it at different times), and a varity of OT's (Did it with Feral, Prot Warrior, and Prot Paladin's on Elites). Kael was done with Two Protection Warriors (one as the Kael MT), a Feral, and a Prot Paladin.
In T6, I decided to push the limits of our protection paladin, and found paladins the equal of warriors against bosses. Different certainly: but fully capable, and just as strong as a whole. This finalized my views of the tanking classes - all are capable, all are different, none are a threat to the others, and working in harmony (and in consideration of the encounter at hand) has far more potential then blind "X is the best Tank, Y Tank will replace Z Tank completely" ideology.