I would third Srendarrs which has a lot of options for customizing time bars and blacklisting certain buffs. Very customizable and doesnt affect performance for me. Other buff trackers Ive tried were built into a UI mod and affected performance too much.
Action Duration Reminder deserves a mention as well, since it applies a timer overlay directly on your skill bar, and creates a second skill bar directly above your primary one if you switch bars to show what skills are still counting down on the swapped-out bar.
Action Duration Reminder is the best option for optimizing your DPS rotation, imo. It simply shows the duration in a number on top of the ability bar, and even shows your backbar directly above it (as above poster said)
For more advanced stuff, I use S'rendarrs. For example, I use it to show the brief timer until Warden Shalks activates. I also use it to show debuffs on myself.
Action Duration Reminder is the best option for optimizing your DPS rotation, imo.
I don't think this is true anymore. Fancy Action Bar seems to be what most top pve players use. The permanence of your two bars shows you what you don't have up as well as what you do, whereas with ADR you have to memorize which slots are passives and what the priorities of active abilities you can't see are.
I use FAB with Bandit's UI to move my improved action bar over my character so it's close to my cursor where I'm actually looking for targets and mechanics, since your toon blocks your view of those anyway. I also squished my resource bars (using bandits) and Combat Metronome just above my action bar in order to read it and my skills clearly.
I can't prove that it's the best setup but my best parse (Turning Tide) is 124.9k on necro and I think it went a long way towards that, and to bringing that power to content.