Follow your customers
Look at the last month. If most new business arrives by phone, an SI receptionist with instant text-back usually pays off first. If most came through your website, social or text, start with a chatbot.
What each does well
A chatbot is cheap to run, great with repeated questions, and can show links, photos and booking times. A voice agent handles people who would rather talk, works when your hands are full, and catches the calls that would otherwise hit voicemail.
Where they overlap
Both can answer questions, book appointments and hand off to a person. Many businesses end up with both, sharing one set of approved answers so the information stays consistent.
Our usual advice
Start with whichever channel brings more revenue, run it for a month, review the conversations, then decide whether the second channel is worth adding.