I hate Microsoft office applications and most FOSS alternatives are even worse. The goal of these templates is to replace all applications I would otherwise need office applications.
These are the easiest to replace. Latex makes writing theses and reports a breeze. Currently, I only have a good report template but will make one for theses in the near future.
It might be tempting to do posters in programs like Adobe Illustrator, Inkscape, or Powerpoint but scripting them in Latex is not too hard and the results can be just as beautiful if you know what you are doing.
These are arguably the hardest to replace, since the plain beamer class is latex is not that
attractive. A good set of slides needs to be minimal but still aesthetic, include slide numbers
and an easy way to embed videos. The only beamer template that I find simple yet aesthetic is
the metropolis template, which I use in my slides. Additionally, beamer allows for a nice
way of embedding a video by linking a local file.