Autodesk Fusion 360 - I confess that I haven't done much with it, but it's free for non-commercial use and it seems to be capable of just about anything.
OpenSCAD -
http://openscad.org - It's a totally different approach to CAD, where you basically write a script that generates the shape that you want. As someone who enjoys programming, I really like this approach, but it does get kind of tricky when the scripts/shapes get more complicated.
I have also used Alibre Design quite a bit, and I really like the UI (it's the most intuitive CAD software that I have tried), but it was $200 when I bought it and apparently it's $1000 now. Apparently they've given up on the hobbyist market. That seems like a dangerous business choice, given that lots of professionals start out as hobbyists.
Please don't PM me with technical questions - start a thread instead, and send me a link to it. That way I can answer in public, and help other people who have the same question. Thanks!