I have two applications... use NoSQL or RDBMS?

I have two applications in the making: one is a budget management tool; the other is a article based places/restaurant guide.

The budget management tool works where users create accounts (e.g. bank account) and create transactions of purchases. The accounts are associated with the user by one (user) to many (accounts) relationship. The same goes for accounts and transaction, one (user) to any (accounts). For this reason I'm wondering if relational database is better here.

The other application users submit travel articles. Users can have many articles which they own. However, each article may or may not have additional meta data associated with it. Examples would be: address, tags, map location. These would be optional fields. Each article other users may add comments also. As the schema is a little looser for this application would I be correct in suggesting NoSQL would be suited here? Otherwise I would need to have may tables for the many-to-many associates (e.g. one article can have many tags, and vice versa)

However, for the budget application I will probably also adopt tags. Is it normal to use a relational database for the strictly relational stuff (user->account->transactions) as well as a NoSQL database for the meta type stuff (e.g. tags - I'd still need to include in their foreign keys though of the relational database tables huh?)

Anyway would appreciate any advice on these matters as I'm still trying to figure out when to use one over the other.