Imagemagick module can generate sharp, clear and detailed images, images generated by imagemagick have better quality than images generated by the PrestaShop's native GD, you will be benefited in a long run by displaying quality good sharp images to your customers.
WebP images have ordinary quality, they are perfect for web because they have a fine balance between good quality and small file size.
Image generated by Imagemagick contains more data, so they are slightly larger.
WebP provides superior lossless and lossy compression for images on the web. WebP lossless images are 26% smaller in size compared to PNGs. WebP lossy images are 25-34% smaller than comparable JPEG images at equivalent SSIM quality index, so using WebP can reduce the content size to reduce page loading time.
Compare with images generated by GD, images generated by Imagemagick are about 5%-15% larger.
WebP images are smaller than jpg, using WebP can reduce the size of content to download of your site, the less content to download means the short time needed for your site to be loaded. But in order to keep the best compatibility with different devices and 3rd party modules, .jpg format images can't be removed, which means the same image need to be saved in two formats, so using WebP will increase storage space.
How to choose?
- If you are running a jewelry, flower, beauty, shoe, bag, toy, clothing, etc. Using clear details images can present your products better, then choose imagemagick.
- If you are running a home & garden, music, etc, Using ordinary quality images is enough for you, then choose WebP.