In terms of SEO, is it better to have a URL broken down by folder, or with dashed names?

URL represented in folder will always be better for reading and well for SEO also, there is nothing difference in either two methods but for human reading it makes lot of difference. If it is easier to read the link there is more chances of user clicking your site (most of the user try to read the url before clicking in the search page result).

Google will give equal importance to both type but to display the result you need more optimization on other things like Anchors, content, keywords, etc. then just a URL. The URL should always reflect your keyword and content. Keep it simple as much as possible.