I really don't know if there is a camera app that could really improve the quality of N7+ pics.
I've tried many: opencamera, better camera, fv-5, even dslr camera pro.
Maybe I'm wrong, but I noticed that most of the best features of those apps are not working on N7+. For example, there's no way to increase manually time of shutter. And so on.
At the end, it seems that the quality is less or more the same we can see with the stock app.
Difference with gcam is huge.
Back to Adobe Camera, I'd give it a try if it had a few more options to set up. I'm not much into fancy filters, but I'm interested in white balance for example, or taking realistic color pics at sunset.