My reasons to use Emacs

• Choosing Software. This post is what originally inspired me to use Emacs, and influenced my tool choices and philosophy greatly besides that.
• (info "(emacs) Intro"). Emacs's own self-summary is modest, but worth reading.
• (info "(emacs) Help"). Emacs has probably the most advanced help system of any program.
• (info "(emacs) Dired"). I do most of my navigation and manipulation of the filesystem through dired. I especially like (setq dired-dwim-target t).
• (info "(emacs) Wdired"). Wdired is a quite easy way to do mass-renaming of files.
• (info "(emacs) Remote Files"). Since Emacs works on remote files, I need only one instance of Emacs to manage all my computation everywhere.
• (info "(emacs) Projects"). A collection of commands for working with projects, greatly expanded in Emacs 28. Especially useful in combination with envrc.el.
• (info "(emacs) Shell"). When I do use a shell, I use it inside Emacs rather than using a terminal emulator. I never use full-screen terminal applications, instead using Emacs or command line equivalents, so I never need an actual terminal.
• notmuch.el. I use Emacs to send and receive mail with notmuch, mbsync, and msmtp.
• (info "(gnus) Top"). I use Emacs to read mailing lists with Gnus, connecting to gmane.io or public-inbox NNTP interfaces.
• circe. I use Emacs to chat on IRC and other networks with circe and bitlbee.
• (info "(magit) Top"). An extremely full-featured git "porcelain".
• (info "(info) Top"). Info is a format for hypertext manuals. In the 90s, many people disliked Info, preferring traditional non-hypertext "Unix-y" manpages. Ironically, today documentation is mostly read in web browsers, which are even less "Unix-y". Anyway, some software (git, Python, etc) has documentation available in Info format, and the Emacs Info reader is a good way to refer to that documentation.
• (info "(emacs) Man Page"). Of course, one can also read man pages from Emacs.
• (info "(eww) Top"). Browsing some web sites from Emacs is convenient and fast.
• (info "(emacs) Input Methods"). With (describe-input-method "TeX") you can, for example, type \lambda to get λ.
• (info "(emacs) Replace"). Even simple "find and replace" is an advanced feature in Emacs. For example, arbitrary Lisp is allowed in replacement strings: (info "(emacs) Regexp Replace")
• (info "(emacs) Pages"). Pages are useful to separate text into sections.
• (info "(emacs) Earlier Kills"). Being able to cycle through previously-copied text is useful.
• (info "(emacs) Rectangles"). Rectangles are fairly useful in a varietry of situations, though if text isn't aligned then a kmacro is more appropriate.