Prismic

I am a full stack developer and designer who has been making websites for 22 years. Prismic started out pretty good for me, but after using prismic for three years here's what I have found: Page Editor Without warning to you or your clients, prismic will force new changes to the page editor on the user. Expect to receive calls from your clients not understanding the new editor and asking why it has changed (and in some instances complaining about the design!).
Once a new editor is live, Prismic refuse to maintain the old editor, expect things to break until you move to the new one. When a new release happens, features are added, but some are removed — with the new editor deployed in a Beta state, and not living up to the hype of the promo videos. Support
 Don’t expect timely support, each email took a day for a response, it seems like they have a very small support team. I feel like I've given Prismic a good go, but am seriously looking at other options for my next headless website.

I've used Prismic on several projects now, and by far, it is my favorite headless CMS.