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
Chrissie