I think much of this is because of the change in how enmity works. In ARR and HW, you had to work for that enmity -- meaning you had to actively keep aggro on every individual mob. What with how tank stances work now too, you don't need to worry about an enmity combo either. You just pop it and go to town. All in all, tanking has gotten much easier than it used to be. A little too easy, if you ask me. I, personally, enjoyed having to actively work for my enmity, and it made sense to me back then that this was the job I was supposed to be doing as a tank.

I'm not too well-versed in which tank is the most enganging at present, but I would think Paladin. Other more seasoned tank-players feel free to chime in.