This is an important point - there is a point where TransferWise becomes more expensive than WorldFirst or a bank, but it is for much higher volumes than most people will be sending on a regular basis.

On average I send between 500-1000 GBP to USD per month on Transferwise and pay 2.50 - 5 GBP in fees. Compared to a wire at a bank that charges 30 GBP fixed + a % on a sliding scale depending on the amount, it's not really competitive until you get over 10k per transaction. But then at that point you can contact TransferWise customer service to negotiate a better rate.