Giovanni, a few days ago I did a side by side pepperoni taste test (pre baked) , since I received my samples of Ezzo pepperoni, 38mm and 51mm.
I also shop at Kroger and included the brands you sampled and also had Sugardale, Hormel and even Kroger brand, but I did not compare the Bertolino or Bridgford uncut, I went the lazy way with only pre sliced, but I did get to compare the name brands with my Ezzo. My conclusions mirror yours,
Bridgford- Somewhat spicy, good flavor
Sugardale, Oscar Mayer, Hormel, Kroger- Somewhat bland in flavor, kind of boring.
Ezzo- 51mm- Very good blend of flavor, tasty, not spicy, less greasy to the touch than the abovementioned.
Ezzo- 38mm calogen- Very good flavor, very spicy with a hot aftertaste, less greasy.
Ezzo turned out to be my personal favorite, but with as much trouble as I went through to get the Ezzo, and the hype generated about it, my minds tastebuds may be a tad biased. I like to think they are not, but can't guarantee it.
Trying to compare all of these samples should prove quite interesting but the true test will be when they come out of the fire and are laying in a bed of molten mozz and prov.