I went crazy recently and bought a bunch from the internet. I was looking for pepperoni made the way it was 30 years ago---with a little spice/kick. Here are my opinions of some of my purchases:
Milan Salami Co.-Natural Uncured Pepperoni: Interesting sausage that includes celery juice powder and smoke flavoring. Good taste, but reminds me more of a tasty sausage than a tasty pepperoni. Worth a try though.
Delallo Italian Style Pepperoni: Probably my favorite even without that spiciness I was seeking. This is a good standard pepperoni, probably similar to what one would find In a good pizzeria.
Volpe Gourmet Pepperoni: This is a small 2-2 1/2 inch diameter chub. I normally love Volpe products, but not this. Bit of an off-taste. Bad batch maybe? It came fully vacuumed sealed, so it couldn't of been spoiled, but it just didn't do it for me.
Molinari & Sons Pepperoni: Came close to the best IMHO. Maybe the closest to a good homemade flavor, as opposed to "standard" pepperoni.