Android Camera Apps

I bought a Nexus 5 a few months ago now and am loving it, save for one aspect - the camera. The Nexus 5 has a very sensible balance of optics, sensor, etc, but is unfortunately hamstrung by the AOSP camera app (which is really the gallery app). So what I am looking for is a new camera app that fixes the problems the stock one possesses. And I'm not just talking about the inconsistency of the auto settings. I need a camera app that has all the features Google forgot to put in. Among other things, I'm looking for ISO, saturation, contrast, and HDR. I want an app that will allow me to take the best pictures possible, not give me fancy scene modes or dozens of filters. Bonus points if it can also shoot video at the 4K 30fps that the Snapdragon 800 ISP supports. Free is always good, but I'm most certainly willing to pay for the best experience. It doesn't have to come from the market either; I'll sideload any home built app that will give me great quality pictures. Any recommendations?

Edit: Control over JPEG compression or the ability to shoot RAW would be awesome, as would control over noise reduction.