It really depends on what you use them for. I know mostly about Transferwise and Revolut.
Transferwise is an Authorised Payment Institution in EU while N26 has an EU banking license and Revolut has both EU and UK banking license. Those are technical differences that have implications on the services they provide but also on the safety of your funds.
In terms of services N26 and Revolut probably offer more services than Transferwise, due to their licenses.
Transferwise has a good transparency track record and attitude while Revolut use more shady techniques (make people register and lock-in to see detailed fees).
Transferwise and N26 have headquarters in EU, I think Revolut created some EU branch to handle EU clients. N26 stopped operations in UK (need new UK banking license).
In the media Revolut does not have a nice image: private/NGO/corporate accounts suspended by rogue algorithms, employees with due salaries and badly treated.
One of Revolut founders and still CEO is family to Russian Gazprom top director – yes, this means higher probability of wrongdoings like money laundering and financing shady characters and actions.
I could not find “bad press” on Transferwise, seems to be another fintech company. Founders seem to be some Estonian Guys.
Belfius and Proximus will create another alternative called “Banx”, somewhere in the second semester of this year. It will be based in EU.
I’d never put my money in Revolut, it’s just too aggressive and even ruthless of a company for me to tolerate. Revolut, N26 and Transferwise and these fintech companies that claim to have been founded to shake the system, not be worse and act worse. So it’s either N26 which I don’t know enough or Transferwise. Hope this helps a bit.