Comma deliminated...depends
What are you trying to do with it. If need searches etc, better to use a database. Of course the data can be picked up by Excel easily from comma deliminated. Depends on what you are trying to do.
ADO/DAO
Think there are a few functions that DAO can do but ADO caren't, not sure about that but vaguely remember reading it. ADO is MS's new improved data access tool, replacing DAO and RDO, but then they are quite likely to move onto something else in due course.
If you have access to both, then it is probably more beneficial to you to go down the ADO path.
$0.02 worth