When comparing MonoDevelop vs Codename One, the Slant community recommends MonoDevelop for most people. In the question“What are the best ways to make a cross-platform application?” MonoDevelop is ranked 3rd while Codename One is ranked 10th.
Ranked in these QuestionsQuestion Ranking
Pro Starting up this program doesn't take as long as starting Visual Studio windows 98
MonoDevelop is free to download and use.
Pro High performance
Pro Open source
Pro Highly customizable
By utilizing lightweight component architecture and the built in graphical designer and theming options you are able to customize a good looking app on any platform.
Pro Java 8 support
Pro Works with all IDEs
Works with NetBeans, Eclipse, IntelliJ, etc.
Pro Multi-platform development environments (via build server)
You can even use Linux desktops to build native iOS apps, no need for a Mac.
Pro Vibrant & helpful community
Pro Attractive pricing
It is possible to build production grade apps even with the free version. Pricing is decent when compared to competitors like Xamarin.
Con No longer supported (deprecated since 2018)
Con Bad formatting
MonoDevelop doesn't offer much in terms of autocompletion and code formatting. Most of the time the automatic formatting that MonoDevelop does is annoying and not really compliant with C# guidelines.
Con The MonoDevelop version that ships with Unity is several versions behind
The version of MonoDevelop that ships with Unity is several versions behind the main MonoDevelop branch. It also gets updated very rarely so any annoying bugs that it may have take a lot of time to get fixed.