If you do not want to write fresh content yourself or you do not have time, I suggest you outsource the job. Make sure whom ever you outsource to is writing them from scratch and not usinga spinner themselves. My favourite are seoarticlewritingpros.com but you can also outsorce companies like www.contentproz.net or www.articlewritingservices.org plus loads of others too.
If you think of your content as a pyramid, the broadest coverage of the topic should be listed first. Then move on to more and more specific as you get further into the page. This is useful to your readers, as they can stop reading and move onto something else once you've gotten as specific as they need. And the more useful you are to your readers the more they will want to read your content.
Spin Rewriter integrates with almost any SEO software. This allows you to post high quality articles quickly and easily. The only drawback is that you only get something like 300 API requests every 24 hours. You can quickly burn through this if you’re doing multiple campaigns. The developer does not currently offer a plan for heavy API users but maybe they will in the future.