QoS - classification - access-list OR NBAR

Hi,

For QoS classification, what should be the best practice? Is it to use ACL
or NBAR?

I am thinking which is better when you consider router performance. I am
aware NBAR is easy to use, less hazel and less configuration.

What are your opinion?

Pros and cons?

I would like to know for real networks, not CCIE lab.

Thanks

Mathew

-- 
Thanks
Mathew
Blogs and organic groups at http://www.ccie.net