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 …
I frequently worked with large numbers of survey recipients and the features that allowed me to cut and paste large lists of email addresses and features for checking email accuracy was helpful in speeding up the process of distribution. Also being able to customize and store various email templates in the tool saved time for repeated surveys.
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.
We used it for the voting process for the board of directors and it was the most convenient way to do it (especially since the report has a timestamp and it was important for us since there was a strict deadline).
We could find out what our client liked or disliked during our meetings, events, or any other actions.