When comparing Emacs vs Neovim, the Slant community recommends Neovim for most people. In the question“What are the best programming text editors?” Neovim is ranked 2nd while Emacs is ranked 9th. The most important reason people chose Neovim is:
NeoVim was a complete rewrite of Vim, with new features added and underlying issues resolved thanks to the Vim code base. The keybindings and configuration are the same as Vim, so the switch can be pretty simple.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Keyboard-focused, mouse-free editing
Emacs can be controlled entirely with the keyboard. While true, I often find the mouse and menus handy for those lesser-used commands. An aide-memoir.
Pro Total customizability
Customizations can be made to a wide range of Emacs' functions through a Lisp dialect (Emacs Lisp). A robust list of existing Lisp extensions include the practical (git integration, syntax highlighting, etc) to the utilitarian (calculators, calendars) to the sublime (chess, Eliza).
Pro It's also an IDE
You can debug, compile, manage files, integrate with version control systems, etc. All through the various plugins that can be installed.
Pro Free
Licensed under GNU GPL.
Pro Self documenting
Emacs has extensive help support built-in as well as a tutorial accessed with C-h t.
Pro Works in terminal or as a GUI application
You can use Emacs' command line interface or graphical user interface.
Pro Great documentation
With 30+ years of use the Emacs documentation is very thorough. There are also a lot of tutorials and guides written by third parties.
Pro Ubiquity
Fully compliant GNU-emacs is available on many platforms, and they all understand .emacs configuration files.
Pro Lisp customizations
With lisp customization, any behavior of Emacs can be changed. Update with pre-release patch can be also applied without recompiling the whole Emacs.
Pro dabbrev-expand (Alt-/)
Dynamic word completion.
Pro Provides org-mode
Advanced planning and publication which can start as a simple list.
Pro Mini buffer
You can pass complicated arguments in the mini buffer.
Pro Enormous range of functionalities (way beyond simple "text editing")
Through its programmability, a very broad range of functionalities can be integrated in emacs, turning it even into a "single point of contact" with the underlying operating system.
Pro Rectangular cut and paste
Emacs can select rectangularly.

Pro Vi keybindings through Evil mode
Evil mode emulates vim behaviors within Emacs. It enables Vi users to move inside the Emacs universe.
Pro Has been widely used for a long time
The first verion of Emacs was written in 1974 and GNU Emacs in 1984.
Pro Visual selection and text objects with Evil
Evil is an extensible vi layer for Emacs. It provides Vim features like Visual selection and text objects.
Pro Support multi-line editing, multiple frame, powerful paren, crazy jumping style
Review the "Emacs Rocks" video.
Pro Cross-platform
Works on Linux, Windows, Macintosh, BSD, and others.
Pro Integrates planning in your development process
You can jump straight from your org-mode files to programming tasks - and back - and build a seamless workflow.
Pro Helm plugin adds even more power to Emacs
Powerful commands, search, and more with the Helm plugin.
Pro Versatile
Emacs is great for everything.
Pro GTK+ widgets support
Since version 25 you can run GTK widgets inside Emacs buffers. One of these is the WebKitGTK+, which allows the user to run a full-featured web browser inside Emacs with JavaScript and CSS support among other things.
Pro Excelent tutorial to get you started
The tutorial you are presented with at startup shows you exactly what you need to get started and teaches you how to use the built-in help yourself later.
Pro Interactive Shells
Emacs has a number of shell variants: ansi-term, shell, and eshell.
Pro Gnus
Managing several large mailing lists has never been easier using Gnus. The threading commands and the various ways of scoring articles means that I never miss important messages/authors, etc. A joy to use.
Pro eshell is cross platform
You can use the underlying operating system shell as a terminal emulation in an Emacs buffer. Don't like the default shell for your configuration? You can change it to your liking.
Pro Excellent Lisp editing support
Built-in packages make editing Lisp source code feel natural.
Pro use-package and org-mode
Missing some neural package that predicts actions
Maybe in the next release ...
Pro Still Vim but with upgraded features and some issues fixed
NeoVim was a complete rewrite of Vim, with new features added and underlying issues resolved thanks to the Vim code base. The keybindings and configuration are the same as Vim, so the switch can be pretty simple.
Pro Better integration with external tools
The core text editor is "headless", meaning it's detached from the user-interface so other programs can hook into it. This enables better integration with IDEs and browsers, where "Vim mode" has typically been a poor substitute because it was a partial rewrite or a partial port at best. One of the advantages of Vim has always been ubiquity and Neovim makes it even more ubiquitous.
Pro Powerful plugin model
Vim plugins have always been useful, but tied to specific languages. Neovim's architecture provides better separation between plugins and the core product, so that plugins are completely flexible and can be written in any language.
Pro Modern code base
As a refactor over Vim, Neovim has greatly improved its code base. For example, some functionality is handled by libuv, the same code base that powers Node.js.
Pro Built-in terminal emulator
This avoids the user having to make any installations.
Pro Active development community
Pro Async plugin execution
Pro Opens a 3Gig Text File in a few seconds
Not many editors can open such a large text file so quickly.
Pro Comes with some good configurations out of the box
Some typical configurations most of VIM users make are default in Neovim.
Pro Fast and light on memory usage
New neovim editor instance starts instantly and you can have multiple editors open at the same time, because id does not require a lot of memory to run.
Pro UI Agnostic
The core functionality is handled apart from the UI, meaning that Neovim can be embedded into any other GUI system, such as Atom.
Pro Work in TUI (Text User Interface)
Neovim can work on terminal, on a remote server over ssh.
Pro Easier to pick-up than ever
Don't believe it? Try typing vimtutor in your command line right now.
Pro Even more powerful since 2019, because of additions such as vim-coc, TabNine, fzf, skim
Vim gets stronger every time command-line tools get stronger. This isn't even it's the final form.
Pro Config file is where it should be
I don't like having dotfiles or dotdirs in my homefolder unless they're needed. Configs should be in the .config
dir in their respective folder.
Pro Built-in file-explorer and ability to make splits and edit multiple things simutaneously.
This makes editing multiple files at once, moving code around so easy.

Pro Terminal mode is very convenient for testing code in a split window
Cons
Con Learning curve is long
While it's better than it used to be, with most functions being possible through the menu, Emacs is still quite a bit different from your standard editor. You'll need to learn new keyboard shortcuts.
Con Sometimes the extensibility can distract you from your actual work
If I ever want to lose half a day, I'll start by tweaking my .spacemacs config file.
Con Keyboard combinations can be confusing for new users
For example, for navigation it uses the b, n, p, l keys. Which for some people may seem strange in the begging. However they can be changed easily.
Con Documentation is not beginner-friendly
Although lots of good built-in documentation _exists_, I have after four years of Emacs as my primary editor not figured out how to actually make use of it, and rely completely on Google / StackOverflow for help.
Con Hard customization
For customization, you need to learn Lisp
Con A lot of jokes in this serious software
Con Using Emacs on a new machine without your .emacs file
Con Poor feature discoverability
Con Limited cross platform support
Neovim is not available for many legacy platforms
Con High effort to customize
A lot of time and effort is put in to make it specific to your needs.
Con Requires Brain Mode Switching
When editing in vim, you have you use the vim keys; when editing in every other window on your PC, or in Word or Excel or other application, you need to use the standard system key combinations. Learning the vim combinations can actually make you SLOWER at everything else.
Con Consume brain energy for editing that should be used for logic
Text editing in vim can be great once you've learned it, but it requires thinking about combination of commands. In other editors, you don't have to think about how to delete this part of code. You just think about how to implement a feature, what is a good design for this code. Even after you get used to using vim, it still requires your brain for editing.
Con Ambiguity in extensive documentation

Con Split the VIM community
Moolenaar to be blamed for. If he opened up the development for vim to other bright minds, no fork would have happened. As it is mostly compatible with vim, it is not such a big issue.
Con Poor support for external tooling
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