I find cornichons a bit intense, and prefer larger gherkins, sometimes sold as 'dill cucumbers'.
My dad was a German emigre and told me that when he was young in the 1920s (jeez, that's a century ago now!), kids would buy them wrapped in paper to eat like icecreams on hot days – and mild ones really are nice eaten like that. From English shops, I think Polish ones are best.
Like others, I reckon the pastrami portion size is deliberately understated on packaging so as to cut the allegedly 'suspect' content, especially saturated fats, sodium in general and nitrite in particular.