bitcoin-qt

I encrypt wallet.dat w/15 character password using qt and have many backups
Best backup is a paper backup I guess.
All hdd and usb drivers might fail

paper might burn

but what is more realistic?

And you could be hit by a car tomorrow, or you might die in your sleep

If your paper wallet, stored in your desk, burns then your pc and whole house will probably go with it.
Only thing you can be sure of is a brainwallet. The question is, what if you have a stroke or something and forget?