I'll give you an example. People love case studies, facts, charts, research data. If you have worked in any field, it's easy for you as for me to gather some data and prepare a presentation of some sort. You may reuse the data creating different content types, i.e., PDFs, slides, charts, lists, blog posts, videos, infographics, etc. Don't forget to provide genuine and abundant information, mention your sources, if they are many put a bibliography section, give dates, offer verification for your facts, include stats.
What type of content is best? Each type serves a particular scope. Prepare articles/blog posts on recent trends in your industry, create fact roundups and infographics for people who like visuals. Collect statistics from different sources, and give your interpretation. The key is to be useful to the readers, easy to digest, and make sense. Don't rely on just one source, and don't copy content from your sources without giving your take on the data. If you need to include the original piece of information, use a quote, and mention the source. If you create content with the above guidelines in mind, you will see other bloggers interested in linking to your content. It's an excellent, white-hat way to increase traffic and get quality links with no outreach.