Again, colours are central to everything that makes the Galaxy S7 Edge’s photos great. For some, it might be a dealbreaker if it seems too oversaturated to their liking. But in this shot, the stronger colour reproduction kicks in very well, especially when it’s placed side-by-side with the iPhone 6s Plus’ duller colours as seen on the moon exhibit.
For low-light photography, go with...
Photography is a very subjective matter. Some prefer brightness, both in colours and light reproduction as what the Galaxy S7 Edge did. Others are going for the natural look, which the iPhone 6s Plus gets.
So it's really situational, and more importantly, dependent on your taste. If you're leaning towards something more natural, the iPhone 6s Plus works. You'll just have to tweak the image ever slightly to bring the brightness to a more visible level.
But if you yearn for that extra colour and want to make your photos look less dull, the no-brainer option is the Galaxy S7 Edge.