Lamb liver is my liver of the moment. I was eating mostly chicken liver since it has about the same nutrients but less vitamin A (55,000IU versus 123,000IU) allowing me to eat more liver!, but I switched to lamb, slightly less frequently than once a week, in order to get the copper (35mg per 500g versus 2.5mg for chicken).
For taste, it's certainly closer to beef liver than chicken liver maybe slightly 'meatier' than beef. I've not had calf liver. I think chicken liver is infinitely preferable for pate, I can't even imagine how people turn lamb liver into a pate but apparently, some do. I also prefer my lamb liver more well done than my chicken liver, but am aware that this is a terrible offence in many people's eyes.