Rhode Island Red and Australorp will lay about the same number of eggs, average 5 eggs a week, if you are getting chickens from hatcheries. The Rhode Island Reds from hatcheries will probably lay slightly better than the Australorp.
I had a discussion recently in the Heritage Rhode Island Red thread, and it seems that the heritage Rhode Island Reds will lay about 175 eggs a year on average, but the Rhode Island Reds from hatcheries will lay about 260 eggs a year, or 5 eggs a week. Although, the heritage Rhode Island Reds will lay eggs for more years and with fewer complications.
Rhode Island Red:
Both of these breeds do well in the cold and the heat. Australorps are generally friendlier than Rhode Island Reds, because RIRs don't generally like people picking them up.
Edited by Bullitt - 4/5/12 at 11:24am