Recs.
Updated
SpecsUpdate
Pros
Pro Great full featured support for Markdown preview (using Markdown-Preview-Enhanced)
Most feature rich markdown preview among editors: import PDF right inside document, using @import *you can run python, it's like having *IPython/Jupyter, full math support, full latex (even entire document) support. Tikz, Viz, GnuPlot, UML, ....
Pro Easy access to lots of packages that extend functionality
Atom has a built-in package manager and an extensive list of packages. There are over 150 markdown related packages available for Atom. Additionally, packages are written in CoffeeScript so anyone that knows CoffeeScript can write packages for Atom to extend functionality.
Pro Extensive list of packages
Atom has a built-in package manager and an extensive list of packages. Packages are written in CoffeeScript.
Pro Multi-line select and edit
Multiple cursors and column selection allow for versatile ways of editing.ctrl + d
will select the current word and each time the command is repeated, it adds the next occurrence of the word to the selection.ctrl + click
or middle-mouse click
will place another cursor in the place that's clicked. Cursors can then be controlled together. This also allows for selecting vertically.
Pro Beginner friendly
One of the goals of Atom is to be a text editor for both experienced and beginner programmers. You can add keyboard shortcuts, change themes, install plugins, and change core settings by clicking through a GUI, or by manually editing config files the old-fashioned way. It has the added advantage of being built using the same engine that powers Google Chrome, so actions like opening and closing tabs feel familiar, even to new or non-programmers.
Pro Great mixed RTL/LTR implementation
Correctly displays mixed RTL(right-to-left)/LTR(left-to-right) within the same document.
Pro Built-in package management allows easily extending functionality
Atom was built from the ground up with the community in mind, and package management is a first class feature.
Cons
Con Cannot open empty editor
It has a known bug which has not been dealt with so far. It opens up the files from the previous session, despite checking in Settings otherwise. This issue is now closed, but as the comments show, it still doesn't work. Slows than even more.
Furthermore, sometimes it starts with a file browser pane opened, randomly. It makes an immature impression, unexpected from the developers of Github.