Variable Radius

Hello. I am trying to build a surface with a variable radious.
I would like to get the same radious in the “sides” of the cube, but variable in the front edge.
I have tried with the Fillet Edge (right model) and get this strange points at front surface that generates discontinuity.

Then I’ve tried the Blend_Surface, but still not happy with the result. Even using 4 Shapes/Slash on each corner I get a strange surface.

I still do not know the precise radius that I want, but I would like to experiment in Rhino. Is a personal project that I will be building with CNC. I am using Rhino to discover which are the radius that I believe are the most convinient.

I appreciate your help. I can also upload the file if that helps.