Depends. Bank is safer but on the other hand offers you lot of services that drain your money. If you don't use bank in any other way, and just save your money there, then bank wallet is better for sure. But I use BTC wallet on every opportunity.
bank is also tracked, for every moment, with bitcoin you can move million and no one will notice it
if for example you move million on dollar in fiat to another friend abroad, i'm sure it will cause soem trouble, no matter if you declared it or not
Technically, itll still appear on the blockchains. Since there are only that many people with that much bitcoin, such a move may be more traceable in reality