When comparing SciTE vs Neovim, the Slant community recommends Neovim for most people. In the question“What are the best programming text editors?” Neovim is ranked 1st while SciTE is ranked 12th. 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 Flexible
It's property files allow for fine tweaks of its behavior, at a global or per language / project level. These textual settings might be confusing for those used to preference dialogs, but prove to be powerful, flexible, and fine grained.
Pro Lightweight
With less than 2 MB of binary on Windows, SciTE starts instantly. Plus, if you don't need all the config, syntax files, blah, there's a 678k standalone .exe version. Nothing is going to beat that for lightweight and start-up times. Stick it in a folder that is already on your PATH.
Pro Powerful
Based on the Scintilla source code editor, SciTE has some advanced features like rectangular editing, simple regular expression search and replace, code folding, etc. It allows the user to launch a compiler or interpreter, and it can also interpret the error messages, jumping at the location they point to.
Lua scripting is key to SciTE's power and flexibility. The Lua scripting language can be used to perform complex text transformations. It's relatively simple syntax and its large user-base makes it a great choice for a scripting feature.
Pro Built-in shell
The console window can show the result of ran commands (like build current file, reporting warnings, and errors), but also accept interactive shell commands.
Pro Portable
SciTE works on Windows and Linux, and it also has a commercial port on MacOS.
Pro Powerful syntax highlighting for numerous languages
Lexers providing folding and syntax highlighting are based on code, not on regular expressions. They support context, nesting, special rules, etc.
Pro Free (except on Mac) and open source
SciTE is written in C++, with lot of contributors, both to the core and to the numerous lexers.
Pro GUI
Has a simple graphical user interface
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 Built-in terminal emulator
This avoids the user having to make any installations.
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 Async plugin execution
Pro Active development community
Pro Opens a 3Gig Text File in a few seconds
Not many editors can open such a large text file so quickly.
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 Easier to pick-up than ever
Don't believe it? Try typing vimtutor in your command line right now.
Pro Work in TUI (Text User Interface)
Neovim can work on terminal, on a remote server over ssh.
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 Comes with some good configurations out of the box
Some typical configurations most of VIM users make are default in Neovim.
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 Treesitter and LSP

Pro Terminal mode is very convenient for testing code in a split window
Cons
Con Hard to config
The configuration is mainly a file-based config, which can be unintuitive and difficult to use for new users.
Con Missing file browser
SciTE's greatest weakness is perhaps the file browser. It does not really have one, just a poor substitute which works a little bit like a terminal window with ls
or dir
commands to show the files in a directory.
Con Customization
No extensions, Themes.
Con Poor feature discoverability
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 Limited cross platform support
Neovim is not available for many legacy platforms

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
