Also, MongoDB in particular has a geospatial data index. So if you were using location data and querying by location (e.g. what's nearby a user's location) that's a great feature. Not sure if other NoSQL solutions have that or if just Mongo.
I also don’t have a clear picture of the structure of the database when I start a project . I want to have the flexibility of adding entries whenever I want.
I’m using mongodb now. I am aware it has issues, but its programming interface is convenient.