Easier breeds would be something in the bantam variety or a smaller breed of a LF. Please do not get your birds from a hatchery. Go to a breeder and get them so they won't be garbage. If you find a breed you will want then go to that breeds thread and ask if anyone has some for sale.
My almost 7 year old son also wants to try chickens (and rabbits) for 4H. I want both as well because we're looking at raising our own meat and eggs to cut down on our reliance on BigAg. So keeping that in mind would it be better if I just let him show a larger egg breed or should I just keep a few bantams mixed in with a LF flock?
Brahmas are good starter breeds. They are calm and docile. OEGB( old English game bantams ) have these quirky fun personalities that any kid is bound to enjoy. Although my roosters tend to get a little over friendly if you know what I mean
. Silkies are one of the most popular breeds of chickens. They have feathers similar to that of a Persian cats fur. Cochins are also another popular breed but I wouldn't recommend the large fowl variety to small kids as they are really big birds same with the LF brahmas and Jersey Giants. Buff Orpingtons are known to be a good calm breed although some roosters have a rep. for being mean. Birds I would stay away from are Sebrights as they are fragile, Leghorns as they are super flighty, hamburgs as my rooster was evil and flighty, and anything else listed as flighty. I would search the breeds section on BYC ( the breeds tab is at the top ) and find one that you like. Autumnhens there are lots of good dual purpose breeds of chickens. I would say Plymouth rocks would be a good choice as they are large but not too large. You could raise multiple breeds of chickens and just show a certain variety and then keep another just for processing. Another thing I would recommend is going onto the hatchery websites and find breeds that you like and then research them and once you decide on a starter breed look for breeders that have them. Most breeders will give discounts to the younger kids to get them started into the poultry. One more thing I would like to add is that going to poultry shows is an excellent idea to find birds you like and to talk to the breeders. Good luck choosing with picking a breed I hope you and your kids enjoy them.