I'm happy that BitBucket keeps evolving as a viable alternative to Github. Alternatives are good. Competition is good and healthy. I personally prefer BB because I like Mercurial more than I like Git. IMHO it provides all the same benefits with a much saner interface. Bitbucket also seems to provide all or almost all the nice features Github has.
And, the biggest boon of BB vs. Github is free private repositories.
I also think that BitBucket has a better user interface than GitHub. I feel that GitHub's multi-level tab design and branch selection makes it hard to switch between the most important views. Also BitBucket's activity stream is a way better: I just don't understand why GitHub doesn't show your own commits and actions in their stream. Seeing your own actions makes it easy to understand what has happened between and since things that you yourself have done.
The VCS software thing is really much less of an impediment now. Both hg and bzr (yes, I actually like bzr most of the three) export to git. I'd be using bzr for all my repos, if it didn't have a bug where "push" meant "push --force". I should look and see if they fixed it.
And in case you have missed it, there is work going on right now to add hg and bzr remote-helper support to git. In particular, if you look at the latest RC announcement[1] for git v1.8.1 we see
* A new remote-helper interface for Mercurial has been added to
contrib/remote-helpers.
and in the most recent "What's cooking"[2] (dev updates) we see
* fc/remote-bzr (2012-12-13) 10 commits
[snipped]
New remote helper for bzr (v3). With minor fixes, this may be ready
for 'next'.
A big hats off to Felipe Contreras[4] who has done a lot of work to get these updates rolled out. Not sure how many others have been involved, but thanks!
The latest RC is available from the usual places, for example [3].
And, the biggest boon of BB vs. Github is free private repositories.