Also symmetry. I get a weird feeling if things aren't the same, hence why I also have a combat log to the left. Which brings me to ...
Also gives me a DPS/TPS report after the fight, and damage in.
What did I notice when these were turned off? That I had more space and less screen clutter!
SCT was doubling up on my incoming combat log, so wasn't necessary. I don't particularly need to see damage output, but I like it anyway so I put the damage min up to around 1.5k so I don't see silly little consecrate ticks.
All I really keep SCT/SCTD for now is warnings.
What I really want with my UI is information I need, with less lag.
Unfortuantely when I raid I need to see everyones health. I also need to see chat, and for personal reasons the incoming combat log. Then theres spell buttons, including things which don't get used often but still need to be seen so I know that they are on/off CD.
Raid Cooldowns is also something I like seeing, but probably isn't necessary any more.
All in all, theres not much other than the default stuff that needs displaying, the main issue is that for it to look nice and be functional, with a personal touch, it seems to create a lot of lag. I find myself using ALT+Z during boss fights like KT when I don't need to do anything but hit him in the face.