LeoCAD currently has a library of more than 1000 different unique pieces (but they don't represent any particular brand), most of them created by James Jessiman (the author of LDraw). It is a free and open source virtual model building application that's well-designed, customizable and powerful.
Here are some screenshots to illustrate the features and user interface of this application:
3D Object Converter
Autodesk Fusion 360
ProfiCAD
VariCAD Viewer
Sweet Home 3D