For me it's as simple as open source projects go on GitHub, private projects go on Bitbucket.
Using Github the way we would like (multiple repos) would put us in the $50 per month bracket, which seems excessive.
Bitbucket, for our use case, has the perfect price point.
I did find it interesting that when I canceled with Github they killed my "paid account" status right away, rather than let me have the rest of the month.
I still have some older repos I keep around because they show how (poorly) I coded way back when, and I don't plan on showing that to potential employers perusing my account. :P