I can second, build123d is awesome!
Splines, fillets, full object-oriented programming techniques if you care to use them including directly referencing properties of existing parts, which is something OpenSCAD fundamentally cannot do.
It has two syntaxes you can choose from, one more oriented toward traditional CAD users (builder mode) and one more oriented toward developers (algebra mode). As a developer, I have found it much easier to work with algebra mode versus builder mode.
I can second, build123d is awesome! Splines, fillets, full object-oriented programming techniques if you care to use them including directly referencing properties of existing parts, which is something OpenSCAD fundamentally cannot do. It has two syntaxes you can choose from, one more oriented toward traditional CAD users (builder mode) and one more oriented toward developers (algebra mode). As a developer, I have found it much easier to work with algebra mode versus builder mode.