I'm starting a surveymonkey competitor to get a piece of the action, if anyone wants to join forces and reap the rewards, please reply and I will contact you.

typeform

Qualtrics (!)

GetFeedback

(Disclaimer: I work there :)

For true enterprise scale, Medallia, MaritzCX, and Confirmit. For business-oriented surveying and analysis, Qualtrics is in my opinion by far the best.

Formstack (disclaimer: I work for them)

SurveyGizmo is another. Have used them for several years. My general perception over the years has been that SurveyMonkey had shinier marketing, but SurveyGizmo had a solid feature set.

SoGoSurvey

Confirmit is the market leader in this space. I've evaluated the offerings of Survey Monkey enterprise and the features are not yet on par with their competitors.

FormCrafts.com

Google has fit my needs just fine: https://www.google.com/forms/about/

Askia. Great company with a great sense of humour.

Disclaimer: I used to work there.

We switched to sogosurvey and we see a huge difference. There are others as well but we picked them.