Oracle Database Discussions

Hi.
Please give some opinion on this:
Wich is the best approach for managing users in a typical three-tier web application, using jdbc:

A) The database has one or two users with the proper grants and privileges to manage data(eg. read_user for selects and admin_user for inserts deletes and updates) In addition, there is a table with all valid application users. The third tier will connect to the database as one of the users, depending on the system login user, via jdbc. When someone new registers on the site, a new row is added to the users table.

B) Database users are also application users. So, when someone new registers on the site, a new database user is created with the proper privileges. No need for users table because application user equals database user.


I know A and B have different security approaches, but appart from that, what are the benefits/drawbacks of each implementation ?
When is one better than the other ?

Thanks a lot.