So I was thinking more about the question of quality content and I have came to answer. Quality content, at least for this site, is content that helps the site grow. This is a new site that is really taking off and content that helps with that is content that I would consider quality. It is quality as it is helps the site. Things like length of the post and if it is only a selfie should not the debate atm. Long well-written articles can be quality as they help the site by showing people there are professionalism pieces on here but we are not limited to that. And when it comes to quality, I think these types of posts qualify.
Contests:
I still think this is the biggest one. Contests work in two ways, they give additional rewards to those who are new to the site and give the people of the site direction of what they can post. As you can post anything on steemit it can be easy to wonder what should I post. But contests help fix that. They also build a community as people are posting about the same thing. And you don't need steem to run a contest you can give away gift cards and such.
SEO Rich Content:
Just as important as a well written article (at this time) is an article that comes up in a google search. The posts on steemit get catalogued on the search engine and this is a lot of links that are coming into this site. Posts that utilize SEO can get higher on searches and get more people to check out the site.
Dev Posts:
As steemit is just one face of steem, posts about new projects or posts that help new projects have value at this time. This is more for programmers but as SMTs are coming out it is something to think about,
Any more you want to add to this list?