For me i used both, i have bitcoin for my investment and sometimes i used this for paying my bills because there is a rebates in every transaction i made then i have bank account for my savings that i want to earn some interest with it and also for my future.
Having money on banks is good to safekeep them. Unlike now, the price is dropping fast and it's making some large coin holders losing money.
it isnt safe at all, there are banks that go bankrupt so you would lose your money because of that, therefore i usually dont trust any banks in order not to lose money