I think the key to this query lies in ' ... developing an application which requires relationship between entities.'
In general 'NoSQL' systems do not support SQL joins, which is what makes it possible to retrieve 'related' data from different tables in a RDMS database. You can have 'related' data in NoSQL systems of course, but retrieving it is not as efficient or easy as just writing an SQL query.
Then you have to consider scale - are you looking to store a HUGE number of items in a single table.
Then here is the nature of the data - is it easy to break this data down into nice related groups of items ?
Then there's the use case - how do you plan to query this data ?
There is a lot to consider, but my starting point would be that if my app depends a lot on intricate relationships, then I'd definitely go down the relational route; but if my data is not so well structured and my use case requires that I'm able to retrieve a lot of semi-structured data items in one go, then I'd think NoSQL.