A few years ago I purchased a 3D printer. What I learned very quickly is that the most difficult part of creating useful or beautiful prints is actually finding, learning and using software. There are a lot of choices but I ended up using just a couple programs. I tend to go with free software or software that offers a free personal use license. The 30 day free trials are not enough unless you already have a very good understanding of the type of software you are reviewing so that you can get something done rather than just try to learn how to do basic things. I am sure many of the paid software packages offer advanced features but with the amount of time that I was investing each day there was no way to learn how to properly use the software in just 30 days.
I started this entry because I am thinking of giving Blender another shot. Blender can do practically anything but it is a steep learning curve. The first time (actually was the second time) it was just too much for me. I just wanted to make basic things and print them.
The program that I started with was OpenScad. This is a very good program and not too hard to learn but it is more like a programming language.
Windows 10 had 3D Builder for free. It does some things very well. I still use it to mirror objects and to merge or subtract one object from another.
The program that I ended up using the most is DesignSpark Mechanical. This program can be downloaded for free and it works very well for any type of functional object. Exact dimensions and calculated curves and angles all can be done well with this program. If you want to do things like sculptures or figures then I don't know what to recommend. I have not yet had any success with creating those types of things. Blender can do it but I have yet to learn how and I suppose I should check out what others have used to create these types of things.