I've always been happy with my UI.
Because i've always pretty much coded it myself, this is way more fun than just downloading something and then setup some settings while they are 1000 more options when you're making it yourself!
My UI is very inspired by Muqq's UI from Ensidia and Elv/Tukui but with a lot of own ideas.
Anyways here's my UI:
Here's my UI just a few weeks off Legion:
My UI during Cata:
As you can see i've made big progress with my UI, and its very fun!