Have you tried any of these since you made this post?
I currently use Strapi and enjoy it for managing content in my database. I created a static site using 11ty (Eleventy) that queried my strapi site for content and that worked out nicely. Payload has caught my attention recently and I really like they offer, authentication, white label, multi-tenants, and even e-commerce to build a store, plus much more. What's even better is Payload can live inside your NextJS app. I'm really like what I'm seeing so far with Payload. Strapi does have a nicer UI, maybe that's because I'm used to using it.
I don't see any of these replacing WordPress any time soon because of how easy WP makes building websites for non technical folks. You still need a frontend with any headless CMS and it's hard to beat WP in that area. WP is great for marketers because they need little to no code knowledge, just install a theme (or page builder) and plug away. You can't get that experience with payload or strapi yet. I can see Payload CMS getting there if they keep doing right.