Hands down, I think Google Forms facilitates evergreen surveys. You can edit and update an existing survey without initiating a new survey each time as with other providers. The link is never broken when you utilize Forms and your content on the survey remains current with that initial link.
Upon welcoming a new subscriber, I link them to a three question form that allows me to get to know them better. I ask what they are struggling with at the moment, what project they are currently working on, and what is one burning question they have about art, faith, reading, writing, and the creative process.
This has been my new strategy. I hope it helps me find those burning dilemmas that I think will provoke readers to think more deeply, as I learn about it in the process as well!