The word system is doing real work in this category. A clock records a punch; a system handles everything that happens afterwards, which is where a small employer's time actually goes. Correcting a missed punch, approving a week, and getting the result into payroll are the three tasks that recur, and products differ enormously on all three.
Correction is the weekly work
Every product captures a punch competently. What varies is what happens when one is missed: who notices, how they are told, and how many steps the fix takes. Run that once in a trial with a deliberately missed punch, because it is the task you will perform most often and the one demonstrations reliably skip.
Approval and locking the week
There should be a moment where a week is approved and then locked, after which changes are visible as adjustments rather than silent edits. Products without it leave a manager wondering every Monday whether last week's numbers have moved, and they usually have. Ask to see an approved week and then try to change it.
The export, which is the whole point
A system that does not reach payroll cleanly has moved the typing rather than removed it. Ask for an export in the exact format your payroll accepts and have whoever runs payroll try to import it, rather than looking at a screenshot of an integrations page. Fifteen minutes of their attention prevents years of monthly annoyance.
Questions people ask about time clock systems for small business
What makes a system rather than a clock?
Corrections, approvals, exceptions and reporting. The capture is commodity; everything around it is the product.
Can a manager edit an employee's punches?
In most products yes. Insist that the original survives and the change is attributed, because unattributed edits are the biggest weakness in this category.
How long should setup take?
An afternoon for a standalone recorder. Longer for anything bundled, and most of that time is decisions about your own rules rather than software.