When comparing Notepad++ vs Geany, the Slant community recommends Geany for most people. In the question“What are the best programming text editors?” Geany is ranked 3rd while Notepad++ is ranked 15th. The most important reason people chose Geany is:
Geany is very lightweight thanks to the smaller offering of features.
Specs
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Pros
Pro Syntax highlighting for a wide variety of languages
Notepad++ has built-in support for syntax highlighting for a wide selection of programming languages.
Pro Light and fast
Notepad++ is a very light program that starts almost instantly. This makes it a great text editor for users that want something that will start the second they open it.
Pro Extendable via plugins
A list of hundreds of plugins is maintained.
Pro Portable
You can get a portable version of N++ and put it on a flash drive or your dropbox account and have your editor, configured the way you like, at any computer that you are on.
Pro Free under GPL
Notepad++ is licensed under GPL, which means it is free/open source software that you can use freely.
Pro Regex replace in selection, active tab, or all tabs
In Notepad++, the user can utilise regular expressions to quickly modify text across multiple files.
Pro Persistent documents, even after exiting the application
If you close Notepad++ (npp), your documents remain even if you haven't saved.
Pro User defined language syntax support
You can define your own custom syntax highlighting rules (or add support for others) .
Pro Easy to use and admin
Very easy to use and personalize.

Pro Multi-line editing
While it is disabled by default, when enabled, it is possible to edit more than one line at a time. This is helpful in many situations.
Pro Split screen
The user can open and edit files in multiple screens within the editor window.
Pro Supports Markdown
If you have the Plugin Manager installed you can search for MarkdownViewer++ and install it via that plugin.

Pro Light and fast
Geany is very lightweight thanks to the smaller offering of features.

Pro Built-in plugin manager
Geany has a built-in plugin manager which can be used to install plugins and add new powerful features to the editor.

Pro Quick search on large files
In Geany you technically search once for a whole search query, unlike Gedit, where once you start typing, the file is searched for in accordance with each substring of what you're typing, all the while leading to terribly annoying lag.
Pro Cross platform
Geany is a cross platform editor, very similar to Notepad++ in Windows.
Pro Build in terminal
Press F5 and code will run without the need to switch between windows.
Pro Actively developed Free (as in freedom) Software
This software respects your freedom.
Pro Real syntax parsing (not just coloring)
Hence it is capable of showing the methods and inner classes of, e.g., a Java source file.

Pro Simple project management
Pro Native
It is a real app and not another frankenstein web/electron app. This means it runs great and doesn't extraordinary amounts of RAM.
Pro Options in the menu are easy to find
For example, there is an easy way to change the font and theme in the View menu. No need to search through several syntax styles like in Notepad++ just to be able to change the used font.
Cons
Con Windows-only
While it can run in Wine, it is native only to Windows. Linux users will have to use Notepadqq instead.
Con Settings confusingly scattered
Examples: try to change the tab size or used font.
Con Annoying update notifications upon start-up
Annoying update notifications tend to pop up upon start-up after not having used the app or machine for a few days. At the same time, they can be easily turned off.
Con Outdated UI
Only the text area can be themed, and it doesn't have as many features as browser-based text areas.
Con Limited new syntax support for new languages
It may be hard to find good plugins for relatively new languages.
Con Session backups not enabled by default
Unsaved tabs will be lost when Npp crashes, unless you first enable the session backup option.
Con User defined language doesn't support triple quote strings
It also doesn't support triple hashed comments. Both styles are overridden by their single character single line version.
Con Not very advanced
Although it has some IDE features, it is not as advanced as some other text editors that can be extended to contain IDE functionality.
Con Windows installer not digitally signed
Con Not many third-party plugins
Geany is not as popular as some other text editors with plugin support. As such it's understandable that it's missing lots of powerful plugins available in other editors.
