When would you pick a NoSQL database over a regular relational one for a new project?

Hey everyone, I've been thinking about what databases to pick for new projects. It seems like most people still just go with a relational database, even with all the buzz around NoSQL. I'm wondering, when have you actually seen a NoSQL option be clearly better right from the beginning, especially for a project that isn't some huge 'big data' thing or meant to be super massive? What kind of things about a new app make you immediately think, "Yep, this needs MongoDB, Cassandra, or DynamoDB" instead of just using PostgreSQL or MySQL? Are there certain ways you need to get at your data, specific needs for changing your schema, or even just what your team knows how to do that makes you go that route?