I have used probably 50 + 3d applications over the years and a lot of them are trying to add 3d printing as a feature , some doing it better than others. Of the ones I have used the easiest by far is Fusion 360, it is basically a re-write of autodesk inventor for easier usage.
If you are coming from a background of never having used these programs there isn't one that is going to be something that you just pick up and click around and make things without a learning curve. Fusion 360 has great learning tutorials on the site and all of it is free. You just have to invest the time in learning . Once you do you will have a new skill set that will apply to lots of other applications.

Programs like openSCAD are great but the downside is the things you learn using it are going to be unique to that program and don't transfer well to other applications. Fusion and similar applications are all based around the same ideas and once you get comfortable working in the xyz world and with things like faces, vertex, edges, you can use any program that is out there.