Customers most agreed on the following attributes:
Keeps the hot shoe clean, never a worry about dirt building and having a bad connection
The Nikon BS-1 Replacement Hot-Shoe cover. I have been shooting with Nikons for over 30 years. Both SLR and DSLR models. I have never gotten this cover with any camera I purchased. Even The D200 was without this cover. That is why I have a drawer full of covers. Cost is small considering the importance of what this cover protects. I bet that a lot of photographers don't even know this cover exhists. A MUST!
This device merely protects the hot shoe when a flash is not mounted on it. It seems well made, although its durability will have to be tested over time. It's overpriced, but much of what Nikon sells is. It will probably be very easy to lose this when removing it from the hot shoe, so placing it immediately into a designated pocket or storage compartment would be a really good idea.
Every camera should have one of these. The item is dirt cheap, and keeps out the dirt. For a couple'a'bucks, get one for each of your cameras.