We have those three breeds, and yes, the Cochins to develop slower. 
We have 6 EEs, 6 Wellies, and 3 Giant bue Cochins. 
2 of the Cochins are very sweet, love to be scratched. One is aloof. All make sqeaky screen door noises and growl. They do not cackle when laying. All 3 are at the bottom of the pecking order.
Welsummers are busy and talk a lot. Not much for petting, but love to peck at anything of intrest - including toes, buttons, etc. Cackle when laying. Middle of the pecking order.
EEs are a mixed bag. Some are friendly. Some not. Our dominant hen (since the roosters were sent away) is an EE, she will complain loudly when you gather eggs. 2 of our EEs are just barely above the Cocj=hins in pecking order and love attention. They can be noisy layers.
All three breeds have layed well in our wet, dark winter. Cochins lay a medium egg, but the shell is so smooth in texture.
I would recommend Cochins (hens) to anyone with kids or living in a urban area where you want happy neighbors.