Hosting of source code is one aspect of a good (bio)informatics library, but other aspects are equally important. If we put this question in perspective of top notch scientific computing, we, or course, match the hosting service with requirements against a journal like the Open Research Computation (ORC). The journal wrote up a number of guidelines, organized in four categories ('support' not one of them (yet); e.g. on documentation for where and how users can file bug reports): Code and License, Documentation, Testing, and Example data. A good hosting service should help the project with fulfilling these requirements. For example, most hosts discussed here provide the means to comply with OSI-license requirements.
However, I am not aware any of them have built-in support for DOAP yet, or FOAF, or any other ontology allowing linking to the project semantically. SourceForge is furthest in terms of functionality, but also doesn't have an app yet for automatic building, such as Jenkins, which will help the project comply to some of the ORC guidelines, such as providing executables as well as testing.
Therefore, my next code hosting service is that provider that has to most functionality to comply to ORC guidelines. Currently, I have to live with GitHub, SourceForge, Google Code, and Bitbucket.
Meanwhile, I have started a Google Docs spreadsheet to summarize compatibility of with ORC guidelines. Contributions are welcome!
Ping me if you like to contribute, and I'll explain what the various meanings are of columns and values.