To me, the key features that make SolidWorks (and Autodesk Inventor) stand out is the use of constraint driven assembly creation. Everything else seems to me to mostly be possible to work around. SolidWorks and Inventor have many, many added nice features like integration with CAM software, ability to assign materials from a database, ability to add things like fasteners and so on. It's a big list, and why people pay so much for it.
But if all you had was the ability to make sketches (using constraints and dimensions) combined with simple feature creation (linear and rotated extrusions, sweeps, and linear/circular/mirror patterns) to make individual parts, along with the ability to assemble parts using constraint driven logic it would be good enough for 90% of what I do as a non-professional mechanical designer.
If anyone knows of such a thing I'd also be interested in trying it... but I have not encountered such a thing yet.