The key thing for any of the free cad software packages you consider is the format in which they save their files. If they only save their drawings in their own format they are useless except as a learning tool.

Nothing wrong with that but if you intend to actually use your work then you need to be aware of this.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now