I stopped doing development for a living three years ago, having moved into security consulting and penetration testing since. Now that I'm setting up Emacs again, I can't believe how much I have missed Magit. While Org-mode and Gnus are the main killer apps for Emacs, they are sprawling. Magit is extremely fast, tight, focused, and beautiful. As mentioned yesterday, I have been doing some open source development recently, and one thing I believe in when making contributions to the code of others is tight diffs. Magit makes it so that the use of a git add -p equivalent is very accessible. 

(use-package magit
  :ensure t
  :pin melpa-stable
  :bind
  ("C-c C-g" . magit-status))

Magit's maintainer is very active, new releases are frequent. I love Magit so much that I contribute to the maintainer's Patreon. It's really that good.