If you only raise one breed you are losing the wonderful world that the diversity of the chicken offers.
Every one has a special breed they really like. I LOVE my red jungle fowl roo and his hens, however they are only a part of my love of birds in general.
Laying hens are there for a purpose and there are a good number of breeds that fullfil this position.
I recently got Yokahamas, speckled sussex, partridge rocks and lakenvelders. I love the all and am in the process of incorporating them into my flock.
I have a good number of different breeds. It is so much fun to watch them pile out of the barn in the morning.
Every one who comes to the farm comments on the pretty birds we have.
One other thing. If you do not have Guineas you are really missing the fun and wacky world of these birds. On our property tney are considered "working" birds as they control bugs that the chickens would mostly pass up.
My favorite laying breed are the rocks. The roos are gorgeous, the hens are gentle and sweet and they lay great big brown eggs.