I've found over the years that broodies generally do better than an incubator, provided they don't change their minds about sitting before the 21 days is up! Rarely get a dead-in-shell with a broody. Once they're hatched, though, I find the chicks under an electric broody grow and feather up faster, presumably because they have longer access to feed and water, as they don't get to go outside only when the hen does over the first days.