I agree with Ruben here that address1 should be whatever the receiver is comfortable will be compatible and cheaper for them to accept. I previously worked at Bitrefill building a bit part of the payment experience, we moved to using segwit bec32 addresses and have not seen any issues and wouldn’t necessarily want to default to a more expensive but more backward compatible address.
One thing we would have liked would be to to be able to set a taproot address so wallets that do support it can opt in to send to that instead.