Sierra is proof-of-concept! For a more refined text editor consider using Brackets
Sierra has a simple and good looking UI. Extra options are placed in the top menu to avoid clutter
Sierra has a built-in browser, so you can convieniently search Stack Overflow without opening a new window. If you do a lot of web programming, you could even use it to test your code!
Sierra can preview images, videos, and audio to ensure that you never mismatch file names.