I started with Japanese Coturnix a couple months ago, and to spite being a complete noob, and not the brightest crayon in the box, I have yet to kill or injure a single bird My hens are outside 24/7 and produce eggs like clockwork. I highly recommend Coturnix.
To save money, and because I am a beginner, I did buy adult birds. I has worked out perfect for me. I didn't have to wait for eggs to hatch, and I didn't have to buy an incubator or a build a brooder. Plus, learning how to care for adult birds is a good step one. Someday I would love to raise a batch of birds from egg to adult. However, caring for the adults is a great way to work yourself up to that challenge. Also, the investment is cheaper if you change your mind.
I've had Georgia Giants, Northerns, & Jumbo Brown Coturnix. I highly reccomend the Coturnix for their mellowness. I still raise them & got rid of the "spastic" breeds.
I'm chiming in to say that coturnix are easy to keep. My experience is "only" with coturnix & button quail (as far as quail goes, anyway. I've had chickens, ducks, geese, guineas...)
Of all the birds I've had in my life, coturnix are the single EASIEST to deal with.