Truenas Scale - Comercial NAS OS. I bit of work to get started, but very stable once going.
Unraid - Enthusiast focused NAS OS. Not as stable as Truenas, but easier to get started and a lot of community support.
Since OP wants to use Docker i would not recommend either. Trunas scale does not support it usefully and the implementation in Unraid is also weird. Also the main benefit of unraid is the mixing of drives, OP wants to raid.