I used to be into Schwartz's Herring as that is where my quest started in the US.
Back home (Austria) there would pretty much always be homemade herring which (in my mind) is just a whole different level.
I have however moved on to Raskin Herring as I like the variety and flavor better. My favorite ones are Pepper crusted, Jalapeno Matjes and their Red Pepper.
Any other good flavors, brands or fish worth trying?