A step towards knowing where your food comes from.

I've raised most breeds out there at one time or another and can tell you mean ones come in all colors and shapes. From experience though, the friendliest feed store breeds are the Cochins, Polish, Buffs, and most large heavy chickens. The flighty ones seem to be a bit on the ornery side like games, most bantams, lehorns and other small frame chickens.
Just my opinion, your millage my vary.

 

Welcome to BYC! We're glad to have you.

My suggestion for a docile, kid-friendly chicken is the Wyandotte. Mine have been personable, inquisitive, sweet, and docile birds. They are also great layers and come in many beautiful colors.

From what I've read (and from lots of other peoples' experience), your Orpingtons and Australorps especially should also be gentle. I'd add in a Wyandotte as well, though!

 

Hello and Welcome To BYC! Be sure to check out the BYC Learning Center, lots of good articles on all aspects of chicken keeping you'll find useful with your new flock. https://www.backyardchickens.com/atype/1/Learning_Center

Not sure if you have seen them, but here are a couple of links to some nice chicken breed comparison charts you might like http://www.sagehenfarmlodi.com/chooks/chooks.html and http://www.albc-usa.org/documents/chickenbreedcomparison.pdf and http://www.mypetchicken.com/chicken-breeds/breed-list.aspx
when you have narrowed down your choices, don't forget to check the BYC Reviews section for member reviews on the different breeds. https://www.backyardchickens.com/products/category/chicken-breeds
For pets,especially for children, Silkies and Cochins are probably the two most popular breeds, they are not very good egg layers but are very friendly and both good broodies. So far as more layer breeds go, the Black Australorps and Orpingtons are really popular lots of people really like these, great pets though somewhat broody). The Plymouth Rocks and Sussex aren't usually quite as broody, I find the Sussex girls to have very nice temperaments. Delaware and Wyandottes are two other popular breeds that are usually pretty easy to get along with. The Easter Egger, often sold as Ameraucana by hatcheries, are a fun breed because they usually lay green/blue eggs which kids really seem to like, and they also tend to be very nice birds.
You might also like to check out your state/country thread to see what people in your area have had luck with. https://www.backyardchickens.com/t/270925/find-your-states-thread

 

Silkies are kids favorites and because they generally go broody often, chicken folk like having them instead of using an incubator. When they are broody, you can swap out their eggs for fertile eggs of any breed and they will hatch and raise them as their own. Due to the fact that other breeds like to bully them, it's probably better to have 2 silkie pullets so they have a friend. Black australorps seem to be popular as dual purpose breeds for laying or meat.

 

Hi and

Silkies are really cool. A lot of people with kids recommend buff orpingtons, they are gentle and friendly.

I'm not sure about the cochins and wet weather but you can try asking here, they'll probably know:
https://www.backyardchickens.com/t/195235/cochin-thread

Good luck!

 

Bared rocks are great cochins are great to most heavy breeds are very kid friendly

 

Welcome to BYC. Glad you decided to join our flock. I've raised dozens of breeds over the past 50 years (including the four you have), and three of the four breeds you have, Orpingtons, Australorps, and Sussex, are about as kid friendly as you will find. My kids made lap pets out of all three of these three breeds, and now my granddaughter (pictured in my avatar) has made lap pets of our Orpingtons and Australorps. Other very kid friendly breeds that my kids made lap pets of are Silkies, Cochins, and Brahmas. Please feel free to ask any questions you may have. We are here to help in any way we can. Good luck with your flock.