I'd say Bank Transfer. You have to provide your bank with all of the supplier's details, and they basically verify the details on their system. So you know the money is going where it is supposed to. Go to the bank - don't do it online - as the teller asked me a few questions and was able to identify the Bank account and verify while I was there. So I knew everything was ok. Takes 48 hours to clear into the supplier's back account.