I choose the latter of two evils, which is Microsoft. MS isn't stupid, and they know that futzing with Github would mean generations of developers never trusting them with anything again. That's not to say that Microsoft won't do the wrong thing, but a lot of people see them as less likely to do the wrong thing than Google, and I happen to agree with them.
EDIT: My first statement is oversimplistic. What I meant by that is Google is mostly interested in advertising and selling data, but Microsoft's business isn't build around advertising(i.e. Bing Ads doesn't appear to be critical to Microsoft's success). Granted, Microsoft is known for selling "data", but I don't see how much of that they would gain from GitHub.