What is a good Tank?
1) Tank that pop his CD and not get one shot?
That not a good Tank Oo, that only require half a brain to understand the job / mechanic Oo
2) Tank that stay alive?
That not a good Tank, that just a good healer that able to keep him alive
3) Tank that can keep aggro?
That not a good tank, that is just a minimum knowledge of what to start with, and spam 3 macro all the fight..
4) Tank that know how to position the monster?
Make monster not face everyone so they don't get raped by cleave or AOE, i mean seriously, that just a common sense.
So in the END, what is a good tank? You can only have a BAD tank in this game and average tank, there is absolutely no way to be classed as a GOOD TANK, and that make the job mega boring and unwanted to play, because tank have very little control in this game. Give Tank a way to stay alive by theyself, or keep his party alive and now you can talk about a good tank and a bad one, or give Tank the same DPS power as everyone.
ATM, the only challenge on PLD or WAR is to stay patient while watching DPS and Healer spamming they mistake.