I had used SurveyMonkey in the past with another employer several years ago. The survey questions used were not great and did not measure what it is we were looking to obtain. At that time, it was also not really user-friendly, but again, this was awhile ago so I am sure they have updated their software since then.
Quantum was provided to us free (basic use) from our chamber--which is why we used it. However now that I have experience with Quantam, I will definitely use it again.