I see not alot of people are talking about PT tanks why is that? I rolled one and love it.
Compared to the other tanks they are the most accessible to pick up and play. Very simple priority based abilities, not many buttons.
Other than keeping up heat screen (which will happen even by not looking for it), mitigation is static, so a powertech doesn't have to spend his resource to increase his mitigation like the other 2 tanks.
High passive mitigation, defensive cooldowns are weaker but far less specialised and more applicable to more situations. When you think about it, kolto overload really only has value when used in a pro-active way, same goes with oil slick. Its almost like we have 1 cooldown and that's energy shield.
I chose it as my main purely because I didn't want to use a lightsaber, but it just happened to be the simplest of the tanks to play. Bothers me sometimes that there is little pride in powertech tanking, but I don't think about it too much.
Also seems to be the least played of the tanks, which further plays into the consensus that juggs and sin player base is of lesser quality. The fact that they are much more popular and much harder to play well, compared to pt's who are far less popular but much easier to play well. In the early days of swtor it was common for some people to consider the powertech the best tank purely because of this discrepancy.