I am not sure about healthier. They are definately easier because Momma does all the heating and caring but then you have all the outside issues to contend with too. I think that overhandling, ( scaring the chicks and making them race around the brooder not gentle handling) heat issues etc can cause stress and stress can lead to other issues but outside there are issues with other hens pecking and Momma can peck at no defined time. We gave Dot 6 eggs. 3 hatched no problemo and the fourth I am not sure what happened - if Momma stepped on it but one hatched and died. Momma scratched and the chicks learned to get out of the way. They are also exposed to mites or lice or other pests too. No, I think the people brooded chicks might have a higher viability rate - A momma chick would also cull anything not viable by tossing it out of the nest or leaving a pipped egg that didn't hatch to die.
Having done both I can say that I think hen raised chicks are more savvy....i.e., scratch at the ground for food from the beginning, understand danger, etc. BUT, they typically aren't handled much and don't imprint or bond with humans as well as brooder raised babies.
The other downside is more chick loss with hen raised babies...predators, mom stepping on them early, etc.
I have raised only two batches of chicks: one artificially indoors, last spring, and another this spring, hatched and raised outdoors by broodies. It seems to me that the naturally brooded chicks grew and matured faster than the artificially raised ones. We handle each chick every day, so they seem just as tame as the artificially brooded ones (and it helped that the hens that were raising them were tame, too....that's something else the chicks seened to learn from their parent).
The ones raised outdoors have been getting plenty of fresh air, sunlight, exercise and "treats" that aren't on the list of approved treats...lots of nasty, juicy, bugs. I was so nervous about what I offered the artificially brooded chicks!
In our experience hen hatched chicks are much more robust than incubated. A few years ago we started switching all our breeders over to hen hatched. Also another big plus is a hen hatched hen will be much more likely to sit herself than an incubated hen.