For me, it’s hands down Flameshot. The best screenshot tool in the world - I’ve got it hooked up to my PrtScrn key for super easy screenshots.

I also love Kwrite as a Notepad++ alternative, and KolourPaint as a MSPaint alternative

  • I’m a bit of a fan of Okular. It just does a good job displaying PDFs and is not annoying. The table of content works well if the document has one. There is text select and block select for when you need to get content out of the PDF. You can tell Okular to ignore DRM with a simple checkbox in the settings, for files that “don’t allow” selecting and copying text or “don’t allow” printing.