I've had about 7 different brands of USB memory sticks, mostly sent from SE Asian companies as samples.

The best one I've used are PNY ones, I have it on my keyring so it gets rattled around a lot, so much so, the colour is chipping off it, but the memory itself is still going strong.

A word of advice, do NOT get any one that comes with a small switch on it so that you lock the drive (much like a floppy disc). These little switched tend to snap off very easily normally locking you drive permanently.