I've used quill quite a bit. It's easy to integrate, the json delta format works decently well, and is pretty straightforward, but one thing I find myself doing whenever I use it is asking myself, "Should I just be using prosemirror?".
I find Quill to be a great stopgap solution for when I need editing and I need it quick, but in the back of my mind I'm always mentally adding that I'll need a migration plan should that specific feature ever grow in requirements.