I've been learning Autodesk Fusion 360. It's very powerful, full 3d with parametric features. Full CAD power, free for hobbyist and startup users. So far I'm impressed, but it does take some work to get used to thinking 3D. Tons of helpful videos, sample parts, and tutorials on line. It can interchange files with other programs, can be used for 3D printing, machining, etc.
I tried a couple other programs, but Fusion has the resources of Autodesk behind it, so it's going to be well supported. And, you can directly import models of items in the McMaster Carr catalog directly into your drawing. I just tried it with some casters, pretty cool!