I used to like new databases like arangodb [1] but my list of candidates now are postgresql and sqlite not just because they are great databases but because I know I'm not going to regret the license they use -- whether it is my own project or I want to open source it or sell something based on it or do work for my employer or a client I don't want to be boxed in.
[1] though mongo is the only database where I was told by coworkers "it sucks! don't use it for your spike prototype!"