Advice needed on best way to display multiple images

Hi Everyone,
I currently use 3 different templates across 20 displays. At the moment I use individual png images designed in Illustrator or Powerpoint which the displays scroll through.
Is there are quick way to set this up? I find it quite time consuming when I need to delete sets of the images. Just wondering if it is easier to create a show in powerpoint or similar and edit that and then just displaying one file.
My screens are usually rotating between 30 and 40 images.
All suggestions gratefully received.
Many thanks