I really like my Black Copper Marans girls. They're big and gentle and lay HUGE beautiful eggs.
However, they eat like pigs and only lay 4ish eggs per week (they compensate in size I suppose) so perhaps they're not best for "production" but I love them anyways. They are not good rangers either.
I'm also rather fond of mutts and various combinations that make up black sexlinks, just because you never know what you'll get and the eggs from each one are different from the others so it's easy to tell who is laying what.
My lone Cuckoo Marans girl is probably the most "outstanding" personality, and my older White Leghorn ladies are the bomb too. These girls get into more "trouble" and are very good rangers.
I suppose I love my BCM girls for their huge distinctive eggs, and my other breeds for their more outgoing personalities. Good to have a mixed flock, best of both worlds!