I like quail better.
Like Rachel said, I can't have roosters either. It's nice to have the option of quail for breeding.
Plus quail are smaller, so I can have more. They need less square footage and don't need runs, so it's easier to house them.
They eat less per bird than my chickens do.
My quail eat out of my kids' hands, whereas the kids are a little intimidated by the chickens.
The 3 I have now are in my kitchen, so they're calmer being in a high traffic area. The only time I've seen them freak out yet was the first time our dog barked by the cage. Otherwise they go about their business. My cats' food is actually on top of their hutch, so the cats are constantly jumping up and down, and the quail don't seem to mind at all. They're also right next to the ferrets, so they're used to noise (although the ferrets DO spend a lot of time staring at the quail!).
I went through all kinds of time and money to get chickens (4 sets of hatching eggs to the tune of $45, incubating for 3 months straight, and getting not 1 chick out of the deal, finally breaking down and buying 6 RIR's for another $15, plus the coop remodel yet to be done), and now I think it was kind of a waste. If I'd known how much I'd like having quail, I would've skipped chickens altogether.
Anyone want some chickens?