I used to work on Sapling and Mercurial while at Facebook. I've been using Jujutsu full time for the last two years.

Jujutsu is in a sense the final form of that style of VCS, which I characterize as making commits first-class rather than branches, and providing powerful tools for managing long queues of stacked changes (git rebase -i is nice but has many limitations that don't exist in Jujutsu).

I go into some more detail in my testimonial, the first one at https://jj-vcs.github.io/jj/latest/testimonials/#what-the-us....