Which network should you accept USDC on?

The same stablecoin exists on several networks. They are not interchangeable, and sending on the wrong one can be unrecoverable.

A network is not a preference attached to a payment — it is where the payment exists. Funds sent on a network the invoice was not issued for do not arrive late, they arrive somewhere else, and recovering them may not be possible at all.

The payer pays the network fee, not you, so a cheaper network is cheaper for your customer rather than for your margin. That makes the useful question not "which network is cheapest" but "which network do my customers already hold funds on" — an expensive network they can pay on beats a cheap one they cannot.