To me this is a really tough question to answer.

I wouldn't say that it is the most boring class since, as many others have expressed, I love playing a tank and find the gameplay involved in tanking to be more interesting than playing DPS or Healer. Now if they had more quirky Support or Utility style classes, I might find those really fun but since support has been sort of watered down and lumped into DPS, not so much.

Now comparing the two tanking classes currently available, that is a bit of a different story. On one hand PLD has very simple and basic skillsets that are detached from each other and many of the defensive abilities are detached from the offensive ones. On the other hand with WAR you have more complex ability rotations that have many of the defensive aspects built into the combat/offensive ability rotations. I can see the two different styles of play appealing to different types of players, and in truth I am not entirely certain which one I like more.

I like the PLD more conceptually as I like the whole holy knight and sword+shield schtick so that makes me enjoy them, but as far as gameplay mechanics I think I might like the WAR a little more.

If I were to say what could be done to make PLD more enjoyable to play (not buffed, but tweaked/fixed) I would do the following.
- Fix broken/bugged skills such as Awareness.
- Tweak some of the very underwhelming abilities such as Shield Swipe ( I like idea of removing pacification and changing it with a different buff/debuff), Cover (shorter cooldown and greater range so that we can actually protect people), Tempered Will (This one needs to either be lumped into another skill like Awareness or completely redone as it has very little use).
- Take another pass at the cross class abilities as many of them are not really useful in high level group content, for example tweak Mercy Stroke so that it has a larger buffer for it to proc the heal and maybe make the PLD crossclass Cure healing based off of STR instead of MND so that it isn't so weak.
- Adding another attack ability that combos off of Riot Blade so there are two different 3 ability combos to rotate between, one being the tanking/enmity one and the other being the mp regen+dps/ot one.

Mainly it is tweak/fix broken and underwhelming skills and add in a little more complexity/flexibility and I feel the class would feel and play a lot better.
Many of these things have been stated by others already but that is my 2 cents.