For me the big benefit of Fintech banks over traditional banks is vastly superior visibility over spending. The one I use is Monzo. Features such as instant spending notifications, instant balance updating, rich transaction information (real merchant names rather than gobbledegook transaction codes, merchant logos, transaction maps, and transaction notes) and spending analytics all combine to make it much easier to maintain awareness and control of spending. Ever since I switched from mainly cash to mainly contactless (tap to pay) spending the above features have all been very important to me. However, if I was still mainly using cash I probably wouldn’t bother using a Fintech bank.
I still have some traditional banks for some features not available at Monzo (e.g. high interest regular savings account, ability to pay in cash and cheques in bank branches) but my Monzo account receives most of my salary and I consider it to be my main bank account.