But overall, I think PT/Van are the best tanks because you can Charge/jump to a target and pull another target to you. ALSO you are ranged so you can keep attacking everything even after knockback without running back at them.
I personally love the utility of PT tanks myself. I agree with others that there is a lot less button pressing to activate defense migration compared to the other two tank classes. This can lead some people to believe PTs are easy mode tanks. To that I say, there is no easy mode to good tanking.
I've been playing my PT (mostly as a ST) for 6 months and I got to say, the combo of jet charge / grapple with both long range (ED, RS, unload) and short range attacks (FS, FT, RP shoulder slam) gives the PT lots of vesitilty. From weak mobs to single target tank & spanking there is an effective rotation and rymth if you take the time to learn it.
My only complaint is the lack of any type of PvE CC. I find this makes it more difficult to solo heroics that you're not over-leveled for. The OP of this thread expressed a desire to be a tank so that he could run a friend or two through 4-man heroics. I personally think CCs and good gear make all the difference when undermanning heroics, hence my original suggestion.