I have tried EEZ Studio and while I feel the lack of some important things like grid and flex design it is by far way more stable than SquareLine. I had some problems with something related to the animations which I can’t remember right now. EEZ Studio is fast and things just worked as expected, as opposed to SquareLine constant crashes and bugs. It just needs time to implement more of the LVGL features and it will be the perfect tool!
Edit: one nice feature from EEZ that comes to my mind is the ability to create styles that later can be applied to multiple objects.