The best online payment service provide between Payoneer vs Wise (formely Transferwise) for Kenyans is definitely Wise.
Wise has low transfer fees and the best exchange rates.
All that you need to receive your money with Wise is to provide the sender or client your Mpesa mobile number and you will receive the money via Mpesa in minutes after it has been sent.
Remitly is also a good alternative of Wise.
For Payoneer, you will have to link your bank account to receive the money. It takes about a week.
Payoneer customer support is close to non-existent.