I have two Australorps, an Ancona and a Black Star. For steady laying, the Black Star is the best. She's sort of a snot, though. I love her, but she has an attitude.
The Australorps are sweet and fat and squishy, and they have a reputation for being the best layers. One of them started laying 19 weeks and is a regular layer. Her sister is the same age now (27 weeks) and still no eggs. I think she is probably an anomaly, though.