From a end user standpoint https://calendly.com/[^] was really good. We used it successfully last year with a bunch of very non-technical people and it just worked. We used it set up a bunch of one-on-ones so it wasn't the typical situation. A few years ago I saw someone try and set their one-on-ones with google forms and the data was so corrupted by the end they had to cancel everything and set things up manually over the phone.