Neither SavvyCal nor TidyCal stands out for advanced scheduling workflows or deep API integrations. Both are described as lacking the power and flexibility needed for complex scheduling, so if you want strong workflow depth, neither is the answer.
Between the two, SavvyCal puts more effort into making scheduling feel personal and easy for the person booking with you, with features like drag-to-select time slots and a cleaner interface. TidyCal's only real selling point is its one-time $29 fee, but that comes with the risk of poor long-term support and no real feature advantage now that other tools match or beat its offer for free.
If you care about a smoother, more thoughtful scheduling experience for your invitees and don't need advanced workflows, SavvyCal is the better pick. TidyCal doesn't bring anything unique to the table and loses out on future updates and ongoing improvements because of its one-time payment model. Skip TidyCal unless the absolute lowest upfront price is your only concern, but even then, you're not getting anything extra for it.