OpenSCAD allows to describe 3D objects as code, which can be organized in libraries and reused in various contexts. It provides an editor with an interactive 3D object view, allowing to quickly understand how the code translates to 3D geometries and refine and debug the model. The great advantage of OpenSCAD is that the designs can be parametrized and adjusted to suit varying needs or to refine a design through successive prototyping cycles. OpenSCAD code can be designed to generated 3D objects from a set of high-level parameters, for example you can write a function that will create a pipe of given length, inner and outer diameter. Another example would be some OpenSCAD function that will generate a wheel hub, and that you can parametrize for various widths and diameters, and then assemble in a larger object, for example a cart. OpenSCAD being quite popular, there are many reusable part libraries available in e.g. ThingiVerse.

What I like best about OpenSCAD is that its use of geometry definition and geometry transformation fits well with that branch of mathematics. If you are familiar with the linear algebra of matrices for geometry and transformation, plus some set theory and graph theory then the whole thing is beautifully intuitive. I like that its pure lines of code and I like to use GIT for configuration management. In contrast I've also used much Fusion 360 which is a visual language, and its lack of an explicitly code base for version control is a nightmare.

The simplicity of making a parametric design , and being able to reference other files in the same design.