I pretty much use Nokia Camera as my main camera app. It has most of the standard settings/controls that you'd look for in a camera. I always set the ISO to 100 when taking a picture in sufficient lighting. When the automated shutter speed increases to about 0.7s, I will then increase the ISO. This is to maintain details in my pictures.
Video mode wise, I think this is the app that triumphs over any other alternative because of the Audio Bass Filter.
I would like to have a toggle between front and rear camera though. Currently the only way is to access the menu. A small button on the screen would be nice.
I also use ProShot a lot. I really dig a the filter editor. Also, the design of the app is nice, especially the tap+hold to change settings quickly. I find myself using it when I want to take a picture in 1:1 ratio, and when I need a self-timer(very useful!) which cannot be found in the Nokia Camera. It also has the timelapse feature, which I have not really played with.
Camera360 is when I want to shoot in double exposure. It was added quite some time back ago, but it seems that not many people in the WP community is using it. The developer(s) of the app created a thread back when the feature was implemented and I don't remember people sharing their double exposure photos. Such a pity.
Here is the link to the thread:
http://forums.windowscentral.com/wi...l-photos-double-exposure-taken-camera360.html
Of course, the filters of C360 are pretty darn good as well. I believe one can achieve amazing photos with the right combinations for double exposures.
I have many more photography apps installed on my phone, but these are the 3 that I use on a regular basis.