I've used SolidWorks for over 20 years and have recently gone through a review of the newer modelers:
My recommendation is Fusion 360. It's a robust product, is well supported and it's free to enthusiasts. The downside is your models are not stored locally. I'm not crazy for the concept, but at this juncture I consider this to be an acceptable compromise.
Design Spark Mechanical seems to have the features to make a good modeler, but is extremely limited in import/export capabilities. The UI is also decidedly user hostile. I cannot recommend it.
A lot of folks are recommending FreeCAD. I can't. It does only parts (no assemblies) and it's a bit rudimentary at this point. Someday it might be a useable product.
OnShape is a good modeler within the confines of it's rather restrictive license for free accounts. You are allowed 10 models and 100 mb of storage for private models IIRC. This might be enough for you, it's not for me. More is available if you make your models public, or pony up the $100/month for the pro version. The import/export capabilities are very good and I use OnShape for doing conversions that other modelers can't handle.
I strongly recommend that SketchUp not be used for modeling for printing purposes. SU can make some very pretty crappy models that will drive a slicer nuts. I've used SU for years for simple woodworking design work. Upon close examination of the "models" (sets of faces actually) in SU, a lot of the faces don't connect (are open). This makes conversion to a solid based paradigm extremely problematic. That's why there are so many tools out there to "repair" stl files created in SU. Trimble seems to be spending a lot of effort adding online features and other pretty parts to SketchUp without fixing what I think is a broken modeler. The license for use of the free version has gotten pretty restrictive under Trimble as well. Strongly not recommended.
I looked a bit at Blender. It might be a good product, but the learning curve is way beyond what I'm willing to expend at this point.
Good luck in your efforts.