You can take any domain that not fare. But if you are adding content in your site then it is difficult to promote your site. So content is must...,....
I really don't follow this line of conversation. Adding content in your site is a must, but why does it make it difficult to promote?
Both are necessary to focus on, if you got domain name related to your profession will help to rank. And next one is content, it is very essential for your site, having good content that attract users to your site is very good.
Content is the area that we should give more focus on. A fresh, unique and informative content can really boost your search engine presence.
I think web page content is most effective now days we can up a website on search result if our website has relevant content to our product and services. Nevertheless we can't ignore domain role it's also very important to promote our services. So both are important for us.
First on domain name (try to get that domain which contains their keyword) and then on content of website.
I think SEO is completely depend on quality link building and unique content on your website because we know content is the king in SEO..Quality Backlinks will help to exposure and promote your website in SERP (Search Engines Results Pages). Best of Luck