Per-pair fee against a plan with an allowance
Wise publishes a conversion fee for each currency pair on top of the mid-market rate: 0.29% from dollars to euros, 0.33% from pounds to euros, 0.45% from Canadian dollars. There is no monthly fee; getting the receiving details costs a one-off amount.
Revolut Business converts at the interbank rate up to a monthly allowance that depends on your plan (€1,000 on the €10-a-month Basic plan), then charges 0.6%, and 1% outside market hours, such as weekends. We use the above-allowance rate so that a large invoice is not understated.
So the answer depends on volume. A $5,000.00 invoice costs $30.00 to convert at Revolut against $14.50 at Wise. Within the allowance Revolut charges nothing per conversion, but the plan itself costs more each month than Wise's fee on a €1,000 conversion, so the allowance only pays off if you use Revolut for its other features anyway.
Neither is a card processor in this model: both are for clients paying by bank transfer. Plenty of small businesses hold both, using Revolut as the everyday account and Wise for the larger conversions.