Framing this as a replacement decision usually produces a bad answer. The realistic outcome for most SMEs is that automation absorbs the repetitive share of a role — the triage, the copying between systems, the first response — and the person keeps the part that needs a person.
Compare against a measured baseline, not an impression
Before either decision, measure the current process: how many cases per week, how long each takes, where it waits, and how often it goes wrong. Without that baseline you cannot tell whether a hire or a workflow helped, and you have no basis for the second decision. Most teams discover the volume is either much smaller than assumed — in which case neither option is urgent — or concentrated in one step that is cheap to automate.
Automation has an operating cost too
A workflow is not a one-time purchase. It needs monitoring, occasional tuning as the surrounding tools change, and an owner who handles what it escalates. That cost is real but flat, which is precisely why it compares well against headcount as volume grows — and poorly against it when volume is small.
If you want the arithmetic rather than the argument, the ROI methodology guide sets out how to model both sides with assumptions you can defend.