Hi @hole19, good question, there are a lot of differences in quality and compression between the various plugins out there. The Compress JPEG & PNG images plugin is very much aimed at simplicity and great compression results in combination with quality images, so many users really like it very much. WP Smush is one of the oldest plugins, and it was taken over by WPMU DEV that is why they have so many downloads. In the past compression with WP Smush wasn’t that good though, so a lot of users switched, but maybe it has improved in the meantime. EWWW has tons of configuration options and also supports gallery plugins like NextGEN and GRAND FlAGallery. EWWW can be also be connected to the cloud to achieve very, very good optimization of images.
Hope this gives some insight in the different image plugins out there.
