The second link although ugly is less "guessable" if you want to skimp on the authorization check. That aside, sometimes an entity might not have a natural key

The second link although ugly is less "guessable" if you want to skimp on the authorization check. That aside, sometimes an entity might not have a natural key that can be slugified (e.g. an invoice), in which case UUID is better. Also, using a generating/looking-up a UUID might be faster?