Corsair - three of them so far. Very trustworthy and well made. I think most decent brands are fairly safe buys, though some have quite poor quality cases. The Ebuyer reviews make interesting reading; Sandisk and Corsair are well liked, though some people have issues with some of the Kingston models. Kensington, I know little of to be honest.
Be wary of carrying one on a lanyard if it hooks onto the lid rather than the body; that's an easy way to lose the drive if it falls out.