Best for image compression. You can compress image size completely according to you. It gives more features like manual compression, auto compression etc. which makes it more handy to use and also increases its efficiency.
EDIT UPDATE: So I've used the photo compression app now as well, and its just as good as the video compression app. Would highly reccommend both of them!! -- Great app snd super simple to use! You can exit out of ads almost instantly.. Definitely one of the best compression apps I've used..
Compressed and then replaced 370 photos on my phone from around 12mb each to 500kb each. It took about three taps on my phone. Can't recommend enough. Had to watch two 5 second ads between the compressing and replacing. It was well worth 10 seconds on my time for the results that I got.
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.