I’ve been using Rhino3d since the 1st beta release in 1998 - if you are a student, or have a student in the family, I’d seriously recommend. Rhino depends heavily on user feedback to make improvements. One of the things I love - besides both 2d and 3d design capabilities, is that it can import/export almost any CAD/CAM file type.
One of the free softwares to get in the game is Sketchup, google it. It is a fairly decent program but the free version does have some significant limits. There is also a 3d warehouse for existing sketchup models. https://www.sketchup.com/ Pretty intuitive and great for basic shapes.
I’ve worked with a bunch of other programs, autocad, Fusion, etc. My recommendation is to pick one and stick with it.