Google Forms - Good for a couple of questions
Survey Monkey - not a good choice for embed since it's not responsive or mobile optimized
qzzr - amazing for quizzes that have alot of images and hold 10-15 questions. optimized for mobile and responsive. white labeled once you pay for subscription. unlimited quizzes.
Engageform https://my.4screens.net/#/my/dashboard - looks flash, b2c focused
survey planet - not bad, easy to use.