Cal.com is better for teams that want the lowest per-user price, a free solo plan, routing forms on the team tier and the option to self-host, since the code is open source. Calendly is better for teams that want the most polished setup, the widest set of integrations and an admin experience non-technical managers pick up in an afternoon.
For a team whose main question is cost, neither one removes the per-seat bill. Cal.com is about 25 percent cheaper than Calendly at every headcount under 30, but both grow in a straight line with the team. That is where a company-priced tool is worth a look, as long as the team works in Google Workspace.