Hello

and Welcome To BYC! You've gotten some good advice and links from above posters. X2 on also try posting in your state thread for local birds
https://www.backyardchickens.com/t/270925/find-your-states-thread This time of year, a lot of people are culling their older birds, so be sure you are getting birds hatched this spring (started pullets, or POL as posters above mentioned), not spent hens... you can get older birds, but they will probably be molting and will not lay again until next year and won't lay as well as younger birds.
Breed wise Orpingtons and Black Australorps are popular and lots of people really like these, they are great pets though broody, Plymouth Rocks, Sussex, Delaware and Wyandottes are some other popular breeds that are usually pretty easy to get along with, they all decent layers and lay different shades of brown eggs. If you like colorful eggs, the Easter Egger, often sold as Ameraucana by hatcheries, are a fun breed because they usually lay green/blue eggs and they usually also have nice temperaments. Depending what you want chickens for, for mostly pets, Silkies and Bantam Cochins are probably the two most popular breeds for kids, they are not very good egg layers but are very friendly. For egg numbers alone, the Red Sex Links / Production Reds (Golden Comet, Red Stars, ISA Browns etc) for brown eggs and the commercial White Leghorns for white eggs are probably the best layers around.
As for breeds, 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 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 many of the reviews mention temperament.