Hi Aleksandar Bencun, thanks for the suggestion. KeystoneJS v6 is one of my initial choices, but it lacks some features like i18n, and singleton so I decided not to go with it (both features are on the roadmap though).
I went over it in my first article How To Choose The Best Headless CMS For Your Blogfolio?. There, I made some comparisons between KeystoneJS v6 and other CMS on the market, you might want to take a look at it!