After a few years I still use Listary as my main search/launcher. It's very quick, has a very nice look and great system of filters and projects. There are problem with new version to be released, but I'm talking about version number 5.
Everything - Everything. Locate files and folders by name instantly. Everything. Small installation file. Clean and simple user interface.
Keypirinha - A lightning fast and flexible keystroke launcher for Windows. No installation required (portable).
DocFetcher - DocFetcher is a portable German/English open source desktop search application.
Wox - An effective launcher for windows. A full-featured launcher, access programs and web contents as you type. Be more productive ever since. Wox is free for use and open-sourced at Github, Try it now! Download .
FSearch - A fast file search utility for GNU/Linux based on GTK+3
Alfred - Your To-Do List. Done.