Some thoughts on getting chickens, as I've only done "new chickens" once.
I'm in the "get chicks" camp. That's what I did, so that's all I know.
I used an extra large dog crate for the brooder, and lined it with sheets of cardboard so that they couldn't escape through the bars. That kept the bedding from getting scratched out. It did NOT keep the dust from escaping, however. While the crates aren't cheap, I have a lot of other uses for one, and they can be used as a quarantine pen, broody breaker, etc. (I used it to harden off seedlings for the garden; no loss to rabbits last spring!) The bars are really handy for hanging feeders, toys, whatever.
There is the whole handling/socializing aspect that everyone has talked about. The chicks are all starting from day one, too, regarding their pecking order. I don't know if started pullets are sold as a flock or not.
When I got chicks, we didn't have a coop built yet, so we had a few weeks to figure that part out. If your coop isn't chicken ready the day the pullets arrive, what can you do? Timing is more critical if you don't have Plan B.
Plus, chicks are really, really cute.