When comparing GPLv2 vs WTFPL, the Slant community recommends GPLv2 for most people. In the question“What are the best open-source licenses?” GPLv2 is ranked 7th while WTFPL is ranked 9th. The most important reason people chose GPLv2 is:
Ensures that the software and its derivatives remain licensed under the same license to keep the software free and open source.
Ranked in these QuestionsQuestion Ranking
Pros
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
Pro No disclaimer
It does not explicitly disclaim implied warranties which some rather idiotic legislations appear to follow.
Cons
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.
Con Not fully proven to be valid
It has been used in many open source projects, but is not fully validated, although widely accepted as an open source license.
i.e. Proven in a court of law.