Welcome to the Q&A Forum

This is Megan from the SEOmoz Help Team.  Unfortunately, we don't have a list of sites with the highest DA.  Sorry about that!  I've passed your suggestion over to our engineering team, though, so hopefully we'll add something down the line!

I have a site that is 4 months old. Prior to today the site had a domain authority of 0, and the home page had a PA of 1. I submitted a daily sitemap and the site was crawled daily. If I ever shared an important article I would submit an extra site map and noticed the content in the search results within a couple hours. This is an active, forum based site. I have heard others complain their site is crawled very infrequently. I am not sure if Google treated my site well because it was newer, or had good content, or decent activity. I can just share my experience that the site was crawled quite frequently. Just checking the first site, it has only a few pages. It was designed by a basic site creation software and seems crawlable. Just small sites (around 10 pages) don't change frequently so they don't get crawled often. If the site owner doesn't submit a sitemap letting Google know a change has been made, it may be some time before Google decides to crawl them or finds a link to their site.