I use both for work. SU is like bringing a knife to a tank fight, there is really little comparison. Although you can use SW to make quick models they are a mess and are very difficult to rework. Where it is incredible is getting to the exact thing you wish to produce that is very complex and requires high precision between them all.
SU can do many things, including making files that can be 3D printed just like any other 3D CAD program. SW does not own this domain in any way, lots of students may use it as well as those who work for well heeled companies but if you are not doing complex assemblies with critical relationships, it's not worth your money.
I print and machine parts from both programs, they look identical when they are done regardless of which program they are drawn in. Autodesk has a suite of free programs you can use to make files for printing you may wish to try.
A well drawn part in SU will print just fine, you need to ensure its a solid to not have problems. Use the least geometry possible and you will be much happier.