Spend some time reading about breeds. While BYC has descriptions of chicken breeds, I really like the descriptions
here better. They have a nice, standardized format, and do a pretty good job of being even handed and complete. You can use this linked site to search for info about nearly any chicken breed.
Everybody has favorite breeds, which makes it difficult to simply ask for recommendations.
You have to decide what is most important to you about the chickens. Do you want eggs? Do you want brown, white or colored eggs?
Do you want them to be friendly and calm? How old are your kids? Will they want to cuddle chickens?
Some breeds are much more cuddly and friendly or calm than others. Some breeds lay vastly more eggs. Some of the highest production breeds, however, tend to suffer more reproductive tract issues as their bodies have been pushed to the limit, or beyond. How upset will your kids be if one of the hens gets ill and dies? (how upset will YOU be?)
Do you want the chickens to free range to supplement their diet? Look for that info as you read about breeds. How many hawks and owls do you have in your area? Start paying attention now. You will almost certainly lose one or more hens to hawk attacks if they free range much time. You can read articles here about how to improve their chances by adding shelters for the hens. But you can also improve their chances by choosing breeds that are more predator savvy -- which is to say, more skittish.
Any choices you make will all be balancing different values and interests against each other. But that's what makes chicken math go! You get 4 chickens and suddenly discover another compelling breed that you really wish you could try, and .... suddenly you end up with 20 chickens instead! Beware of chicken math!