Also, BitBucket supports Mercurial, which is used by some major academic projects (for example, the Jikes Research Virtual Machine). I also personally prefer Metcurial, so having the choice is great.
mercurial (via tortoise, and even cmdline) is much easier to use for simple things (branches, merge, update) I think git has more bells and whistles, but a lot more painfull for novices to use
I have a student account on GitHub and I use BitBucket for private repositories with my employer. I prefer the GitHub website so much more. Better design, better graphs, you can get an overview of who in your team has committed in a time period (Pulse), better README, better commit history layout, more service hooks (no Trello support for BitBucket is annoying considering we use Trello for organizing and managing our projects), to mention a few.