keyword: "domain"
Sub-domain\domain, it doesn't matter. If you're wanting to use a Moz metric instead of a PR perspective, there's still DA no matter how you cut it. Sub-domains are taken from a esthetic standpoint only from what I've done and seen, and until anyone provides a side by side controlled comparison, I'm going to stick to my guns. The time of easy EMD's, sub-domain, directory and filename matches for spamming are well over.
Who can remember a sub-domain from anything outside of the Internet Association?