Neither really, in terms of google, key words are totally moot. Your description is best utilized when you think about serp related CTR. It does not help your ranking with Google. hope that helps, Nigel
In past few search engines using them but its not that much useful.But its good practice to keep those meta keywords relevant to the page.
I personally think it is still important to include both meta keywords and meta description. Both will help your rankings on some search engines. The description is more important as it also affects your click through rates.