Great roundup! When I found out Gutenberg was going to be JS based I was concerned about the difficulty of using the new APIs to create Blocks based on my past experiences learning the post meta, Customizer, and settings APIs.

When BlockLab came out I got a huge confidence boost that much of my PHP knowledge could be retained and was able to see just how open Gutenberg was to development.

Once I got started, I learned very quickly that it is possible to write Blocks with simple JS and that the well-documented WordPress Handbook is the underrated holy grail for Blocks development.

The custom controls that require so much code to create in the Customizer, settings, and post meta API can be done with a few lines of JS, and without the hassle of data sanitization is a HUGE deal.

While these plugins make the barrier to entry into Gutenberg development easier, and they have helped me, I would encourage anybody in the business of custom Blocks to give the Blocks JS API a shot and see what is possible on your own; you might be surprised at what you can accomplish!