An AI assistant or an online booking system for a salon?

Each one solves the half the other cannot

A booking system shows availability and takes the appointment. It answers nothing: a client who does not know whether a patch test is needed, how long to allow, or whether their last set can be filled will not find out from a calendar. An assistant answers exactly those, and cannot take the appointment unless it is connected to the diary - which is an integration project, not a setting.

Buy the booking system first, and this is not modesty

If there is no booking system, an assistant can answer the questions and then has nowhere to send the person: it captures a name and the front desk calls back, which is better than silence but is not what anyone bought it for. With a booking system in place the assistant's answers end in an appointment. The order matters more than either purchase.

What the assistant must refuse either way

Whether a treatment suits a particular person - skin condition, hair history, pregnancy, medication, a reaction last time - is assessed in person and in light. A booking system never pretends to answer that. An assistant can, and a confident answer at ten at night reads as permission, so a salon should require the refusal in writing and test it before going live.

What to publish before buying either

Patch-test intervals, how long each treatment takes, arrival preparation, the lateness rule, the cancellation window and the correction window. Both products get better when these exist, and neither can invent them. A salon that writes these down first will find out how much of the problem was never a software problem.