Sublime Text is a widely used editor that describes it self as a sophisticated text editor for code, markup and prose.
Download the .dmg file and drag-and-drop it to the Applications folder.
Use CLI to open file
Let's create a shortcut so we can launch Sublime Text from the command-line
$ ln -s /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl /usr/local/bin/subl
Now you can open a file with
$ subl myfile.py or start a new project in the current directory with
$ subl ..
Sublime Text is not free but it has an unlimited evaluation period that comes with notification pop-ups asking you to buy it, if you wish to remove the pop-ups you can purchase the tool here.