Either party (the employer or the payroll company) could be disclosed. However, it would be more meaningful to have the name of the employer listed. After all, what significance would "ADP Payroll" have on your statement if you were paid this way?
The employer is the party obliged to make the payment for services. The employer obtains the employee's authorization for the direct deposit. The employer is the party that is barred from requiring direct deposit to a specific bank as a condition of employment. The employer is the party two whom the employee would go if there is an error in pay.
The employer is the party usually named on the statement, in my experience.
As you might guess, I vote for having the employer's name listed in the Company Name field of the ACH block header (and that's what determines what prints on the bank's statement.
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John Burnett
Cape Cod Bank and Trust