I have used both Atom and Bracket as well, but they don't come close to the speed with which you can get work done on Sublime Text 3. You want to code, click the ST3 icon and bam, you have your editor open instantaneously. Near zero startup time. For me, that's the biggest selling point. And I didn't even talk about the time-saving keyboard shortcuts.
There are other added benefits such as clean UI, minimap code view, amazing plugin support, and a super active developer.