Ask HN: What is best site to get customer feedback?

I am preparing to get some user feedback on my site, and have the following options: https://www.usertesting.com/ https://userbob.com/ https://www.ubdi.com/individuals/how-it-works https://www.prolific.co/

Has anyone used any of the above services? If so, I appreciate your feedback.

Alternatively, I could buy some FB or Google ads to my landing page and try and setup a hangouts call with every person that enters their email address. Any feedback on this?