New is always better. But you can get very good deals with Refurbished laptops. They usually come with 90 days of manufacturer warranty, So you can return it if you find any issue with the laptop. I never tried a used computer so I can't say anything. But basically, It depends on the deal!!
BTW, With that budget (300$-400$), You can get a way better 15.6 laptops. Bigger screens are very comfortable for editing photos and videos.
For example:
Here
And if you are interested in AMD laptops with bigger screens:
here