Typora will give you a seamless experience as both a reader and a writer. It removes the preview window, mode switcher, syntax symbols of markdown source code, and all other unnecessary distractions. Replace them with a real live preview feature to help you concentrate the content itself.
Looks great! Not sure if it’s still actively developed though … it’s been around since March 2015, and it looks like it hasn’t received any big updates ever since. Available on all platforms.