@JeremyCherfas I recommend VS Code over Atom in general. Atom has some performance issues, due in part to an unfortunate approach to plugins.
Per Stack Overflow 2018 Survey, VS Code also now has a bigger userbase, too: https://insights.stackoverflow.com/survey/2018/#development-environments-and-tools
(For PHP in particular, you could also check out PHPStorm: https://www.jetbrains.com/phpstorm/ )