i'm back from a week end in Amsterdam, took lots of photos in the dark, and i'm really pleased with the photos... hdr+ does a really great job at removing noise while OS works very well too... i don't understand all the critics for the nexus5 camera...
I don't have a Moto X, but I bet if you go over to their forum, you can find a bunch of threads talking about how terrible the camera is (like there are in every phone's forum), then look at their photo tread and find a bunch of great shots (like there are in every phone's forum).
Here are some photos I salvaged from my Cruise last week. These are all Nexus 5 HDR+.
My Nexus 5 got a saltwater bath and never recovered. Luckily I had been backing up my photos via USB OTG, so I did not lose a lot. New Nexus is already shipping as we speak.
Pictures from a recent Vegas trip. I don't know what I'm doing by the way, so anytime my finger isn't in front of the shot or it's not blurry, I'm pretty happy.