I am a big fan of hardware enabled write protect switches on flash drives.
My favorite is the Kanguru FlashBlu30 with Physical Write Protect Switch.
You can certainly find cheaper thumb drives, but the write protect locking switch on this disk ensures the safety and integrity of this drive.
It's only 8.0 GB, but at least it's USB 3.0. I don't buy these for space, but rather for the write protect switch.
Just flip the switch between locked and unlocked to toggle the behavior.
Another nice boon is that this device has a red activity LED to indicate reads and writes.
Thanks to this device, I can create bootable USB drives that are read-only. This could be helpful if I'm booting to a live USB and want to ensure I do not accidentally delete files on the USB drive.
You can feel relatively safe that the drive will not be compromised by viruses as well, since it is read-only when the write protect switch is enabled. You could also store important data on this device and ensure you will not accidentally delete it.