Do you have a Verizon store you can go to, or another store that carries the phone so you pick one up? Internally, they are identical with the exception of the storage (which you've already researched, right?).
You can't make your decision based on our feedback. There's only one objective difference between the two: storage. You either need 64GB of storage or you don't. If you do, your decision has been made for you: Ballistic Nylon. If you don't, then it's all personal based on how the phone feels and looks to you in person in your hand. At first I was peeved that I was being forced to buy the BN because it was the only phone with 64GB. Then I walked into the store and picked up the Metal Glass Fiber versions. I was disappointed in the feel and the "in person" appearance. Photos of them look great, but I didn't care for either the red or black once I got my hands on them. The Ballistic Nylon version, on the other hand, looked and felt great.
So, for me, the Ballistic Nylon looks and feels the best, and has the added benefit of double the storage. Once you walk into a store and pick up both models, you may fall in love with the Metal Glass and wonder what the hell I was thinking. But you do have to have the tactile interaction to make an educated purchase decision, IMO.