If you're looking for a purebred chicken that will live and lay longer, then go with the RIR's, but if want a chicken that's a better more profitable egglayer, usually even laying through winter, then the sexlinks are the way to go.
I agree Sexlinks are the best layers, My sexlink is almost 2 years old and she lays everyday. Unlike my others breeds that are barely laying at all and some actually aren't..