No ones asked you the most important questions.
1. What exactly are your storage requirements?
2. How complex are your data entities?
3. Do you have many users? If so, what sort of queries/updates will they be doing?


I've been using SQL for over 10 years now. I can't say I like it. Discussing the merits of ANSI SQL (not many!) is irrelevant at this stage.
BTW why do people forget that the optimiser is the center of a RDBMS. If it is a poor one (are you listening Oracle and Sybase? :) following ANSI can be the worse thing to do. Granted I haven't used Oracle for a couple of years the last time I did the query optimizer was given up and we reverted to rules based queries.
Another problem with some RDBMS's is that they require almost constant DBA work to keep them going.

Give careful thought to your data requirements. Bear in mind that a RDBMS is geared to larger data loads. If your requirements are fairly small then the DBM modules would probably give better performance.

gl