Hi @mara, Sublime is much more stable and faster than Atom, in my experience. I tested Sublime, Notepad++ and Atom for a long time, and Atom is by far the less stable of the three. If a free license is a must-have, I would go with Notepad++, otherwise Sublime 3 is the best of the bunch, and as noted by @danr you can test it for as long as you need in order to decide if it's worth the 80 $.
One final note concerning plugins: Atom has a reputation of being the most customizable and having the most plugins, but I didn't find Sublime fall short on the quantity of plugins. It even has a Python IDE (!) (not very aptly named Anaconda, though it has nothing to do with CA Anaconda) with code completion, tooltips, docstring opening, jump to method definition, linting and others. Of course, no such plugin is needed for R, because RStudio is the best IDE 