Taxonomy Fields or Vocabularies content types ?

Hi,
Building a large content-tagged site, I hesitate between two ways of tagging my contents (assuming a same vocabulary concerns many types of contents).

In "vocabulary" creating page, I can set content types it concerns ; then I can tag this content with terms of that vocaublary.

BUT

I also set up a few cck fields to that content which allow the same tagging...

Which method will be the better to then present my contents per vocabularies and terms filters ?

Thank you.