Did you know that Bitbucket offers an unlimited number of private repositories for free? I didn’t until March of this year.
What a free account offers
Below is a table which describes what a free account for each service will get you. “Public” and “private” refer to public and private repositories, and “users” means the number of folks with read or write access for a single repository.
GitHub charges for private repositories and Bitbucket charges for multiple users.
My guess is Bitbucket targets corporations—Atlassian owns Bitbucket and Atlassian makes software for large organizations—while GitHub targets freelance developers and start ups. Again, just my guess.
Bitbucket for private repositories
This is a no-brainer. It’s an unlimited number of private repositories for free.
GitHub for public repositories
Although I knew about Bitbucket for as along as I’ve known about GitHub (circa 2009), I had no idea Bitbucket allowed an unlimited number of private repositories until March, 2015 because I never go there. I think I speak for most folks when I say that when I want to explore code shared among the developer community, I go to GitHub.
Keep posting your public source to GitHub for maximum exposure.