Tony
Given the choice, I wouldn't use a flash drives to transfer the pictures. You'd be better off opting for an external USB laptop drive - cheaper and much more capacity.
However, if you do insist on using flash drives, then they are all pretty much OK. My employer insists on Kingston for 2 reasons.
1 - the make memory so chances are they know what they're doing
2 - encryption - we have to use encryption for any off line storage
Sandisk make a good line - a lot of photographers swear by their CF/SD cards, their USB Flash Drives are very good too - the ruggedized freedom range have a useful lanyard on them.
As an aside, I was speaking to a colleague of mine who has stopped using DVD's for long term storage as they degrade over time. He now uses USB Pen drives and has a shelf loaded up with pen drives all numbered and catalogued.