Ask HN: Should I use Contentful or WordPress API for building a static site?

I'm thinking about freelancing my skills and designing websites for local groups in my area. I don't want to have them come to me to update their website everytime they need the content changed though. I was going to use a CMS like Siteleaf until I found out about Contentful and headless WordPress (not designing a site with WP but just using their API to pass data to a site). Right now, I'm leaning towards WP because it's a bigger name, but I glanced at Contentful's website and it looks interesting. I'm not sure which one to use, so what are the benefits of each? Also, are there any other interesting alternatives?