When comparing GPLv3 vs GPLv2, the Slant community recommends GPLv3 for most people. In the question“What are the best open-source licenses?” GPLv3 is ranked 4th while GPLv2 is ranked 7th. The most important reason people chose GPLv3 is:
Requires people building on your work to licence it for others to use.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Copyleft
Requires people building on your work to licence it for others to use.
Pro Ensures that the software does not become proprietary
Pro Ensures that derivitave works are also protected by copyleft
Ensures that the software and its derivatives remain licensed under the same license to keep the software free and open source.
Pro Guarantees that all changes are given back
Pro Ensures that the software does not become proprietary
Cons
Con Limits the developer's ability to package or use other libraries/software
Con Copyright
Requires people building on your work to license it the same way you did. Good if you want to pull their code into your project, but issues for potential end users can arise.
Con Ensures that the software does not become proprietary
Con Cannot be linked with other licenses
Software licensed under the GNU GPLv2 is incompatible with all other licenses, with the exception of GPLv3 in most cases. This means that code from a GPLv2 program cannot be combined with code under another license in the same program.
Con Long and complicated
The license is very long and complicated, making it hard to read and comprehend. However, there is a simplified version available here.