I'm moving away too (er, have already moved). I have chosen RethinkDB and am very happy with it so far.
I think the most important thing to me is that the Rethink guys haven't lied about the database's capabilities and limitations.
10gen did. Both in their marketing and in their sales pitch to us when I worked at Aol. Never once did anybody mention a global write lock when we were talking to them about a write-heavy application.
