When comparing Motion vs Greenfish icon editor, the Slant community recommends Motion for most people. In the question“What is the best free icon editor?” Motion is ranked 1st while Greenfish icon editor is ranked 2nd.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Windows and Linux versions
As it's developed with Lazarus.
Pro Open source
Written with the free Lazarus (open source Delphi like) development environment, the Greenfish Icon editor source code is included in the download.
Pro Portable version and many languages
Cons
Con Unsigned and not commonly downloaded
The application is unsigned as it says UAC (user account control) and when downloading in Edge, smartscreen says that is not commonly downloaded and can have malware.
Con Comprehensive
Because of all the advanced functionality this is not the easiest icon editor, so beginners might prefer a more limited simple icon editor.
Con Dependency upon Python2
It is not a 100% deal breaker but Python2 has been left behind without compunction. The average person downloading this will not have Python2. So it will not install nor run. If it could be statically linked or migrated, then maybe.