When comparing MonoDevelop vs Flutter, the Slant community recommends Flutter for most people. In the question“What are the best tools for making a cross-platform application?” Flutter is ranked 3rd while MonoDevelop is ranked 6th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free
MonoDevelop is free to download and use.
Pro Starting up this program doesn't take as long as starting Visual Studio windows 98
Pro Open source
Pro Great developer tools debug/hotreload/analyser
Pro Based on Dart language
Dart is a Java like language, easy to learn and startup fast for millions of Java developers.
Pro A single codebase for iOS AND Android
Pro Fast
The developer's goal is to allow people to make apps running at 120 FPS.
Cons
Con No longer supported (deprecated since 2018)
Starting with version 4.x, Xamarin rebranded MonoDevelop as Xamarin Studio, but only for the Windows version of the IDE.
Stable release
7.6.9.22 / September 21, 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.
Con Still in development
According to the website, Flutter is still in its early stages of development.
Con Based on Dart language
Dart is a Java like language, easy to learn and startup fast for millions of Java developers. BUT if you have to learn it ... it's a con.
Con Dart is unpopular and never gained serious community traction like Kotlin or Java
Con Does not support 32-bit iOS devices
If you plan on targeting iPhone 5, 5C or earlier, you can forget about Flutter.