I played a warrior on live from early on all the way thorough PoP and raided all the damn time. Then on an official progression server (fippy darkpaw) I played a raiding paladin. Now, on P99 I'm doing SK.
It was a blast main tanking on my warrior. But let's be real - the defensive disc was really the only reason I was picked over hybrids. In fact, the amount of time and effort I had to put into being geared well enough to MT for a raid was crazy.
As a hybrid I didn't have to worry even as close as much. I was still a fantastic tank in high end groups on my paladin. Aggro was so much easier which made grouping more fun for me. Additionally, having roots, heals, LoH, overall more utility was a very welcome change. Perhaps my priorities changing made it a better choice seeing as I didn't have the same kind of time to devote to main tanking for a guild. I was able to offtank adds and still have fun and meaningully contriubute to a raid scene.
I expect that playing an SK now will be similar, if not hopefully a little more fun
[You must be logged in to view images. Log in or Register.] Having the ability to solo is a mega boon. being able to pull effectively with FD will make grouping even more easy. Travel will be a breeze with invis. and in the end I'll still be an excellent tank for the thing we do most often - group for exp!
What I'm trying to convey here is that the type of tank you want to play highly depends on what you want to get out of it. Do you want to main tank? Do you intend to put in a lot of time? Warrior would be your best bet. Looking for more utility but still want to tank? Maybe you don't have as much time to burn? Roll a hybrid.