I'll add my opinion on each tag. But in summary, I say we should get rid of all of them except [tag:usb-drive].

1. [tag:usb-drive]

    Excerpt:
    > For questions regarding storage drives that connect using a USB port. 

    This tag is used a lot, especially since it has [2 synonyms][1], [tag:flash-drive] and [tag:pendrive]. Currently, it has 1315 questions tagged with it.  
    **This one we should keep**.

2. [tag:usb-storage]

    This tag has no excerpt with 187 questions tagged with it.  
    I would recommend making it a **synonym of the [tag:usb-drive] tag** above. *The excerpt of that tag even mentions storage drives explicitly.*

3. [tag:usb-c]

    I'm not sure if this tag has any use at all with 101 questions and 0 watchers.  
    I would **recommend deleting it** and retagging with [tag:usb].

4. [tag:usb-device]

    This tag isn't being used much with a mere 34 questions and 0 watchers. It's mostly used for external devices plugged in through a USB interface. Nowadays, almost all external devices use a USB interface for connection as long as it's not a very old machine or Apple product (which recently is also shiting to USB).  
    I would **recommend deleting it** and retagging with [tag:usb].

  [1]: https://askubuntu.com/tags/usb-drive/synonyms