Worse are the projects that actually expect you to look at the tests as the only form of docs. This indicates that the author does not care about whether you have an easy time using the project, and that it was only written for their own amusement.
A well done project website shows that the author wants you to have an easy time working with the code, and is "putting out a welcome mat".
Compare mercury: https://github.com/Raynos/mercury with vue: http://vuejs.org/.
mercury is likely the "better" framework, with it's reactive approach, but in vue, there is attention to detail and documentation through and through. So vue is inevitably what I recommend to backend developers or others who just want to get something done.