I've evaluated most of the image compression apps listed and by far the best to me was Compress Image. Ease of use is fantastic, and I especially like being able to see a live preview as I adjust for file size. Great app. Reached out to developer re an aspect of the app and got a quick helpful response - another plus
Excellent app and usable for free. There are in-app purchase options for what I assume to be more advanced features, something I will be looking into at some point when I have the need for more customised results.
It's a great app. There's one unclear design element IMO: after a batch compression, one might expect "delete" to delete the originals, rather than the brand new files. Having a "delete originals" option would be nice (different from Replace, allowing an inbox > outbox workflow.)
I don't know about other apps for compressing images. But this app, Compress Image is the best app so far. It is so easy to use and result is amazing. I highly recommend this app as it is both effective and efficient.