I've been thinking lately what should I preferably use for data storage and archival. I will say in advance that I do not use flash memory as the only storage media - I also keep my data on the hard drives and optical disks - flash memory is but one of the several backup solutions that duplicate each other.

For the flash memory however I do have a choice - to use a generic USB thumbdrive or a SD card. Are there any indications that SD cards may be better and more reliable? From browsing people's review on the web I see that many complaints about USB sticks have to do with them completely failing, losing file system and stop being recognized by the OS. At the same time, most of the complaints for SD cards deal with just write speeds not holding up to the promise - failure reports are but a portions of those for the USB sticks. Are SD cards indeed more reliable?

Am I also correct in my assumptions that SD cards use higher grade NAND chips than USB thumbdrives? At least, for class 10 cards, because the specification dictates the minimum performance and the manufacturers have to preselect better chips. While it is common for USB sticks to promise high speeds "up to XX MB/sec" but the reality is they very often deliver speeds 2-3 times less than promised. Do SD cards get better NAND chips and USB thumbdrives receive the discarded chips?

Any thoughts would be appreciated.