I think its a personal preference. If you are confident in your husbandry skills, raising a baby up to an adult is a very rewarding experience. If you are a little unsure of yourself, purchasing an adult might be a better choice, as they are a little more hardy and can handle a little more inexperience than a hatchling. Another perk of buying an adult is that if you plan on breeding, by buying an adult you cut out a year or more of waiting time. Good luck with whatever you decide to do.