In terms of a business logic implementation, I think KeySurvey had the most extensive features. Granted, I haven't used a paid version of SurveyMonkey, but for our purposes, the customization KeySurvey offered us (implementing our corporate colors, fonts, and logos) was one of …
It's a convenient tool for questionnaires, surveys, and other reasons when you need to get people's feedback. We really enjoyed using this instrument, even though it can be a bit overwhelming at times. Also, it might take some time to create a survey if you have complicated business logic implemented, but that would take some time using any kind of instruments.
We have had several moments when we needed the support (mostly it was when we were working on creating business logic for the survey and sometimes things didn't work as we expected them to). The KeySurvey support team was very friendly and helpful via chat and in case they couldn't solve the issue right at that moment, they always came back to us with a solution to our issue
In terms of a business logic implementation, I think KeySurvey had the most extensive features. Granted, I haven't used a paid version of SurveyMonkey, but for our purposes, the customization KeySurvey offered us (implementing our corporate colors, fonts, and logos) was one of the best features and it looked professional. Also, the name "KeySurvey" kind of sounds better and more business-like for clients from enterprise companies.