The DB holy grail is one of my favourite things to talk about. There isn't a single correct answer here, it depends entirely on your requirements. It's really about horses for courses.
First things first, is your data relational? If yes, go the RDBMS way. I just love the discipline that a RDBMS store enforces - foreign keys and not nulls for examples.
NOSQL gives you a lot of power (in the sense that, there are not really a lot of constraints from I've seen), so it's easy to get sloppy. Use it only if you understand it.
But, like Joe said, most companies these days usually have a combination of a SQL store and a NO-SQL store. At my previous job, the 80% of the data was in Postgres and the rest was in Mongo.