I want to add my two cents here:
I started with Beta 4 on PC. Once official launch had been going on for a while, all of the PC Copies had been taken, but there was a surplus of PS3 copies. I picked that up because A)It was an MMO, B)It was there, and C)It's not like the PC version has exclusive content that PS3 can't access anyways.
Even after I switched back to PC, I continued playing on a controller. I use Logitech Dual Action, which at times feels clunkier than a PS3 Pad. And you know what? I can tank just fine. I don't need to use a control scheme used by the 90th Descendent of the Lich King Slayer or the Lord of All CoD Headshots.
In the end, whatever console you play on will not matter to me. The only thing that I give a damn about is whether you can perform your role when it counts. Capiche?