Ardens

GIMP - unlike Krita - which is made for drawing - this is made for photo-editing. It’s like Photoshop. The learning curve is a bit steep, but it is really powerful.

Inkscape - the best vector graphics program out there. So easy to use, and so powerful.

LibreOffice - simply the best office suite there is (IMHO). I was a MS-office user for years, but since I switched, I haven’t looked back…

Thunderbird - a brilliant e-mail program, which also handles contacts, newsfeeds, calender and more. It’s available for multiple platforms, like Android, Windows, Linux and so forth…