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Nikon is mechanically superior (strong and durable). Kenko supports electronic coupling. Pick which is important to you. The electric coupling of one of my Kenko tubes died after a few years of use. Another has a loose part.
If you are using tubes with reversed lenses, go with Nikon to get a stronger, more stable attachment. Remember that the oldest (pre-AI) tubes should not be mounted directly on some newer cameras. They can have an AI tube in between. I have used a compatible PK series tube with some older pre-AI tubes stacked on the non-camera side.