|Actually the correct order of longest lasting/most available media is in the following order|
The difference here is between transfer media [floppy disks/usb sticks] and storage media [tape/cdrw/dvdrw/hard drive]
Transfer media is for short term storage and assumes they do not contain the only copy of the file [though you should maintain copies of any importand files in more than one place]. Transfer media can die at any point in time and are unrecoverable.
Storage media on the other hand should last 5 to 10 years with CD/DVD being the best in that it is not effected by magnetic sources whereas tape and hard drives are.
Let's put it this way, after an EMP [electromagnetic pulse - usually the result of an upper atmostphere atomic explosion] the only media not affected will be cd/dvd media.
The moral of the story: transfer your pictures to DVD not usb memory stick.