DVUI - repo is a great one that I have used. It is actively maintained and has all the widgets you would need to get started. This would be my recommendation. Fizzy is built using DVUI, so it is a proven system.
There have been a few more created recently that you can find in Ziggit. There have been a couple posts in Showcase. I can’t vouch for those as I have not personally looked into them.
Knots looks promising as well