I like private keys instead of passwords in theory, but in practice, I'm scared that I'll misplace the private key file, rendering all of my data lost forever. Private keys can also be lost (stolen laptop?) or misplaced. Or what if you're traveling and your laptop gets busted, how do you safely and quickly transfer a private key from your home storage to where you are? I'm not a crypto-expert, maybe these questions all have easy answers--but they're not obvious, at least.

Memorable passwords are in your brain for the long-term, and can't be lost or stolen. (Well, aside from improbables like torture.)