Of course, it all depends on the type of modeling you do.....engineering..architecture...sculpture. I have used several that include Sketchup, OpenScad, TinkerCad, and Cubify Invent.. I would forget Sketchup as it is a surface modeler and after you spend lots of time making your model just right, it won't print or chances are it won't. Don't invest your time, like I did, learning Sketchup. Having said that, I think TinkerCad is a good first time user program for 3d modeling. It's free and gets you the basics. It works with combining easy shapes and using 'holes' to remove material. This creates some impressive designs. My current favorite is Cubify Invent. It is an awesome program with lots of features and is only $48. I think Cubify Invent is a good second program; easy to learn and lots of good videos online via You Tube. Then, there is openScad. It's programming 3d modeling. Yes, it's difficult to learn but it's great for parametric modeling where it does all the calculations for you based on input parameters. Hope this helps...happy printing!