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

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.

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

Askia. Great company with a great sense of humour.

Disclaimer: I used to work there.

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.

typeform

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

Formstack (disclaimer: I work for them)

Qualtrics (!)

GetFeedback

(Disclaimer: I work there :)

FormCrafts.com

SoGoSurvey