I've used NeetoCal for scheduling numerous customer conversations and even personal calls.
I had used Calendly and YouCanBook.me in the past -- while Calendly was far too expensive for its feature set, YouCanBook.me had a generous free plan but was limited in how I could setup my availability calendar.
NeetoCal in comparison has all their features and is free! I can't think of any reason to use any other calendaring tool at this point.
Neeto's UI is simple and consistent across the board. And it is rich in words! That was important to me. Recent SaaS tools have generally given up on language and instead rely on iconography. It is often hard to figure out what something means, and hard to locate the settings we need.
Compared to that, every time I use NeetoCal, I'm welcomed with detailed well-written notes as I'm setting up a recurring open meeting, or while configuring my availability calendar, and when reading through help articles.
It has two other things (again, in the free plan!) that I'm excited to try out next: Webhooks so that it can talk to my apps, and a close integration with NeetoForm so I can have multi-step forms as part of my meeting acceptance flow.