For my UI I use:
Action Bars - I've tried both and I really prefer
Bongos2 over Bartender, I just think it is much more user friendly. To compliment Bongos2, I use
CyCircled to give the buttons a more pleasing look.
Unit Frames - I like to use
PitBull as I think the frames look very nice and the add on allows for very easy configuration of them. The frames even come with a built in threat meter, I never use this though because I swear by Omen.
Mini Map - I use
SimpleMiniMap to clean up a lot of the unused buttons and give it a new look.
I also use
FuBar, but I use it as a dump for my other add ons instead of using it to tracking statistics.
I'd post a link to a screen shot of my current UI, but I am posting from work as I usually do and don't have any screen shots here. I might post one up when I get home.
Question: Does anyone know what addon changes the cooldown timer on your buttons from the clockwise fading shaded area to a number value? I've seen it in a few screen shots on this site and have never been able to find it. Thanks in advance if you know.