For egg production coturnix are the all time masters. Lil machines they are. The average coturnix hen can produce 300 eggs per year under the right conditions.
As far as the "bird or the egg" question .... If you like to hatch and have plenty of time go with eggs, If you're not well versed at hatching, or in a rush, or want to save time and money go with live adult or late adolescent birds.... 17-19 days average incubation time. lay in as early as 6 -8 wks from hatch to production of eggs. These guys are the egg laying worlds "instant gratification" Everything happens fast and in high gear with coturnix. They need 14+ hrs of un-interupted light a day to lay eggs--- artificial full spectrum light works fine. They love perpetual sameness! Lemme rpaet that.... "They love perpetual sameness!" This means.... same food, same pen, same roommates, same everything--- break their routine and they will make you pay the only way they can---"BAD KEEPER! NO EGGS FOR YOU!" So.... if you go with live adult birds you are in fact changing their environment--- totally changing it that is! Care to guess what's most likely to happen?
LOL, Thats right--- BAD KEEPER! NO EGGS FOR YOU! this can last from 1 week to a month or more. So dont expect to go buy hens on saturday and have scrambled quail eggs for mondays breakfast unless you buy both.