This is a moving target. It's hard to know where the failure point of a thumb drive is ... unless you destroy it. And by then, it's been replaced by a whole new line.

As previous posters have said, redundancy is key.

FWIW, I have been using SanDisk thumb drives for many years and have never had a failure. I have a couple of Verbatims too, but they are annoyingly slow.

I used to use cheapo thumb drives; some years ago, when I dropped one of these onto a wooden floor, it permanently scrambled. Note to self: don't use no-name stuff for important data.

My $0.02.