There is no definitive answer, as some people prefer to use covers and some don't. Ultimately, it is a matter of personal preference.
That being said, there are some potential benefits to using a cover. For one, it can help to protect your Kindle Paperwhite from scratches and other types of damage. Additionally, a cover can provide a bit of extra grip, making it less likely to slip out of your hands.
If you're interested in using a cover, we would recommend checking out some of the options here: https://www.amazon.com/Kindle-Paperwhite-Cover/b?ie=UTF8&node=7068140011.