Framadate is simple to use, is ad-free, runs on free software and is operated by the Framasoft team - a non-profit helping make free software accessible.
Fully free unlike Doodle
Looks promising, but right now (2019) is very buggy and unfriendly:
All I need to schedule a meeting.
I want to like framadate. Libre and easy to use, but the design has not kept up with mobile screens. Desperately needs a responsive redesign.
Our users have written 5 comments and reviews about Framadate, and it has gotten 76 likes