In my experience it depends a lot on the specific corridor — what's cheapest for me sending to Brazil was noticeably not the cheapest option a friend found sending to a different country. I stopped looking for a universal answer and just compare the actual quoted rate (not just the advertised fee) each time for my specific route.
I send money home fairly regularly and the options all seem to have different trade-offs — traditional bank transfer, dedicated remittance apps, digital wallets. Is there an actual "best" answer or does it just depend heavily on which two countries are involved?