Well, this is just what I think would be best- I'm not the most experienced, but I hope I can help
The breed: You need to decide what you want the birds for. I'm guessing its eggs, so you'll want a prolific layer, but you also want a friendly one for your boys (no better Christmas present in my opinion!)
Bluebell Chickens: The Bluebell hen is an autosex hybrid developed by Meadowsweet, (hence sometimes called a Meadowsweet Bluebell) by crossing Maran & RIR. As a hybrid it cannot breed true and its eggs/chicks will revert to type according to the cockerel used to fertilise them. So they are not pure breeds, but hybrids produce the same number of eggs over fewer years. They lay light/pale brown eggs, about 300 eggs a year. They come in Large fowl and Bantam
Maran: As mentioned above, they have given their blood to the Bluebell, and are completely pure bred. Marans are prolific layers, laying the distinctive 'chocolate brown' egg is you select the right colour bird. They lay approx. 250 eggs per year. Cuckoo Marans are probably the most common of the breed and come in standard, silver and gold colours. There are also black marans, black copper marans, white marans, wheaten marans and blue marans amongst the other many colour variations. I have a Cuckoo Maran, and she is amazing. We get an egg a day from her, and she has only missed 1 day since she started laying 12 weeks ago- a little star!
Black Rock: Again, a hybrid, so will lay the eggs in a shorter amount of time. The Black Rock hen is an extremely attractive bird, predominantly black with variable amounts of chestnut colouring around the neck. She is very productive, laying up to 280 eggs a year in ideal conditions. She is bred from very special and uniquely selected strains of Rhode Island Red and Barred Plymouth Rock from a single hatchery in the East of Scotland. The breed was stabalised in Scotland, and there are some chicken breeders who arn't selling you what you think you are getting. So look around and make sure they are definately selling you what you think you are getting.
Warens: The ISA Brown or ISA Warren - is a hybrid chook - a combination of pure breeds, bred together for a specific purpose. As far as I know, Warrens are what you and I would know and recognise as birds used as battery hens.
They are a lovely docile medium brown/ginger bird and an excellent layer - bred for maximum egg production. They are ideally suited for free range conditions, and for small gardens and you should get approximately 325 brown eggs per year. Warens are a very ‘people’ friendly docile bird, ideal for the first timer and for people with children. They love interaction with us humans. You will always have company if you start digging in the garden with a Warren.......they appear from no-where and literally sit on the shovel waiting for a worm!
Hope this helps with the breeds- will post again on your other questions
CC xx