I haven’t seen Montgomery or Keens here. I’ve had three Quicke’s cheeses: Devonshire Red, a mature clothbound cheddar, and elderflower cheddar. I liked Devonshire Red best of those and elderflower cheddar the least. The elderflower cheddar was okay, but I’m not generally fond of cheddars flavored with things like that.
Green Thunder is the other Snowdonia cheese available to me. Garlic and herbs in that one. I might try it if Black Bomber suits me. Interesting that you say that BB is the best known Welsh cheddar. Collier’s is what I see most often here. I really like that one, too.