In short: OFX is expensive, not transparent and very slow
I compared OFX and TransferWise and originally thought OFX had the better offer. I started a transfer with OFX and was shocked when I saw they added a hidden fee of CHF 20. They said it's an intermediary fee (was not shown anywhere on the screen before I hit submit, hence very unfair and not transparent). The next day, I set up an account with TransferWise and transferred the same amount (USD 1000 to CHF).
TransferWise was much faster (one business day vs. five business days). I got CHF 25 more credited to my account via TransferWise, that's about 2.5%...
OFX was a huge disappointment, TransferWise a very positive surprise.