I'll throw something else into the mix, not that I don't love OpenSCAD (I very much do, and it's the only software I can get myself to model anything in to be honest. I've tried every GUI based modeler I could get my hands on and couldn't get he hang of it for the life of me).

Solvespace is a graphical modeler, completely free and open source. It doesn't even need to be installed, just download the executable and run it. Some might call it primitive or basic, but I quite like it. The interface isn't crowded and I find it quite straightforward. It's quite nice for drafting up constraints and linkages quickly to see if they work, but it can be used for much more. No, it doesn't do chamfers and fillets at a click yet, but coming from OpenSCAD I just see that as something I need to plan ahead for, not a feature missing from the software

Just an option if all the code and scripting isn't your thing. Like most 3D modeling software it uses true curves when modeling objects which should technically give it an advantage over OpenSCAD which uses polygonal approximations. The flip side of this that no one seems to mention is that STL files turn those curves into polygons anyway, and OpenSCAD is the only program I've seen that gives you definite control over how accurate the polygonal approximation is. Fusion 360 gives you some vague "high/medium/low detail" option, not sure what solvespace does but you can set exact detail values in OpenSCAD if you know how.