I'm a moderately experienced professional developer. That in no way means that I'm going to pay money for Github, a less-valuable service compared to one that has all the features I regularly use* that I get for free from somebody else.

Also, git annoys me. Thus, Bitbucket, and life is good.

* - Which is to say, source/diff browsing, a markdown-based wiki for some projects, and that's it. Github has a lot of features, but it also has a lot of completely useless features.