Bricscad has everything AutoCAD has and more such as mechanical design (Inventor like) and sheetmetal and full BIM for things like Architecture and all are still just .dwg!

I have been developing on Bricscad for years and it is far faster with a much less buggy API as well. Bootup times smash AutoCADs :)

For reference, AutoCAD base offering is a $2k/year subscription.