Which Is Better ADO or OLEDB?

If you search on this subject you will find several threads already here with many answers/opinions.

From "Teach Yourself DB Programming with VC++ in 21 days" (SAMS)
...ADO stands for ActiveX Data Objects. ADO is built on top of OLE DB. ADO is an OLE DB
consumer. Applications that use ADO use the OLE DB interfaces indirectly.
ADO provides an object model for database programming that's similar to, but more flexible than,
DAO's object model. For instance, you can create Recordset objects in ADO without first creating a
Connection object (which is something you can't do in DAO).
ADO simplifies OLE DB. OLE DB is large and complex; a program that uses OLE DB must use some
complex COM interfaces. ADO is much simpler to use than OLE DB and can be classified as a highlevel
database interface.
Also, ADO can be used with more programming languages than OLE DB. ADO provides an
Automation interface. This enables ADO to be used from scripting languages, such as VBScript and
JavaScript. (OLE DB can't be used from scripting languages because scripting languages don't have
pointers and therefore can't use COM interfaces.)
...

From the same book (ommited ODBC, DAO, RDO and modified the table)
Table 10.1 Comparison of the Database Client Technologies

Object model OLE DB (+) ADO (++)
Nonrelational data sources OLE DB (+) ADO (+)
Low-level control OLE DB (+) ADO ()
Performance OLE DB (++) ADO ()
Code-to-functionality ratio OLE DB (-) ADO (+)

Search for such books that compare technologies and look at the tutorials and the articles on this forum.