All of them are good ways to store your bitcoins securely. Of course, there is always a certain grade of risk as it is for example with condoms, they never give the 100% effectivity, but the 99%-98% or something like that, basically because we humans are fallible.
This doesn't mean you won't fuck because of the possibility you get a disease or get someone pregnant. So go on with any of the methods described above and don't worry too much about it.
Of course, the same as you wouldn't fuck without a condom with some filthy whore you knew in some backstreet you shouldn't have your bitcoins in any exchange online, wallet online or whatever online who holds your keys for you
This doesn't mean you won't fuck because of the possibility you get a disease or get someone pregnant. So go on with any of the methods described above and don't worry too much about it.
Of course, the same as you wouldn't fuck without a condom with some filthy whore you knew in some backstreet you shouldn't have your bitcoins in any exchange online, wallet online or whatever online who holds your keys for you