When deciding on which format to use you will want to answer the question, "What is the purpose of the site map?" Is it for visitors, spiders or both?

1.) If the site map is for visitors as a resource to help them find a small number of predetermined set of pages then you might as well do it on your own. This allows you complete control over the formatting.

2.) If the site map is for spiders to ensure that your pages are easily found the determining factor on which to use would most likely come down to page counts and frequency of pages being added or removed.

For web sites with high page counts or web sites where pages are added or removed frequently then a dynamic site map is the way to go.

3.) If the site map is for both visitors and spiders then again it would come down to page count and frequency of pages being added or removed.

You might even decide to have two (2) maps. One for visitors mapping those predetermined pages and one for spiders listing every page in your site.