When it comes to USB thumb drives there are two primary factors involved; space and speed. They are important in that order as well. Remember functionality wins every time so if the drive doesn’t have enough space it doesn’t matter how fast it is it is not useful. Likewise you an have a large capacity thumbdrive but if its slow then you are less likely to use it even though it is still functional. Don’t discount speed when it comes to USB thumb drives. Speed is a critical factor and will determine how often you use the drive in the end.