For standard CUA editors:
Control + Shift + Arrow-key to highlight words.<p>But I use Emacs so everything I do is a shortcut. Maybe my favorite Emacs shortcut is actually a short-cut framework called Hydra. You enter a temporary state where all key-bindings are shadowed with custom bindings, allowing single key presses to perform anything.
Vscode (and others): cmd+shift+f to search in files, and related shortcuts to navigate through the search results and quickly open the matches files. I use it literally hundreds of times a day often with regexps, especially in projects with several heterogeneous files (scripts, makefiles, Kubernetes manifests, ...). If I had to reach the mouse every time I do a project search, my productivity would plummet.<p>On a more meta, cmd+shift+p to open the command palette so I can execute commands by fuzzy matching, so you can do some random actions without having to navigate the UI manually (typical things I do could be view git log, stash something, stage a chunk of the file, ...).