This is a handmade custom UI i've been using and updating in some fashion since tBC
I've made some modifications to it in the last couple days since this picture. Quartz has replaced the cast bar, and I set up some weakauras for Arcane (mainly relating to burn phases and mana usage). I also scooted the pet ability bar like 1/2 a mm to the left to get rid of that annoying overlap.
All in all I like it, although I'm contemplating ditching my buff mod, since it takes up so much space for no real reason other than it looks pretty. I've just used it for so long, it's weird seeing buffs in any other way. Quest objectives are hidden in raids, but they appear on the left hand side where the raid frames are. Party frames are disabled in raids, but they appear on the bottom left right above the chat box. All my MageNugget frames run along the top of he screen (spellsteal/poly/bomb timer). Focus and Target of Focus are in the space right below my unit frame, to the left of the ability bars.