I have not used the Puritan; they seem to be highly regarded and are quite a bit cheaper than the Niagara. I do own the AudioQuest Niagara 7000 and when I added the AudioQuest Dragon Power cord to the Niagara the overall sonic performance increased with the equipment connected to it.
So, not only are you asking for a comparison to 2 different manufacture’s models, but the power cords used will make a difference.
It may not be a simple question...
ozzy