I worked with CSS Grids back in 2010 when I was working on a Windows 8 app. Since then I hated any other constraint resolver including Box Model, iOS Auto Layout and Flexbox model. CSS Grid is so intuitive you forget how difficult this problem has been in the history of UI engineering
The intuitiveness of CSS Grid is the major appeal for me. I've worked with Flexbox for the last few years and still regularly have to look up the Flexbox reference pages. Perhaps it's just me, but I have found the whole Flexbox naming scheme anything but intuitive.
For the first year or so, I often had to look at this cheat sheet: (https://css-tricks.com/snippets/css/a-guide-to-flexbox/, but now it all feels very intuitive.
The one exception is `align-items: stretch` never works how I expect it to, and I usually end up with a combination of `flex-basis 100%` or `max-width: some px value` with `width: 100%;`