Comment by mghackerlady

I think permissive licenses are fine in some cases (particularly if you're trying to standardise something. X11, LLVM, and BSD are good examples), but generally at least weak (LGPL or MPL) copyleft are preferred.

I'm still torn on what kind of license is best for operating systems, though (the GPL has forced companies to actually contribute to Linux but they also try and get around it in so many ways I have to wonder if a weaker license would be better)