
I have been using SoGo Survey for nearly 7 years for twice monthly mini-surveys for a panel I maintain full surveys two or three times a year for employee satisfaction and other surveys.
It is fairly intuitive to use and its question display logic option lets you set rules to show or hide a follow-up question based on a participant's answer to an earlier question. That really gives you great flexibility in survey designing.
You can save any question into a "bank" and then easily recall and insert it any survey.
It includes a system for distributing survey invitations by email and it automatically processes any unsubscibes (and informs you on each emailing if any of you list has unsubscribed so you cn update your list. Review collected by and hosted on G2.com.
Reordering pages can be somewhat cumbersome. Review collected by and hosted on G2.com.