For young kids starting out, I usually recommend one of the single shot rifles like NEF in .243. It teaches them safety, taking their one and only BEST shot, etc.

For older 1st timers, I usually recommend a bolt action like the Howa with a decent scope on it. Calibers depends on what they think they can handle, and their physical size. I never recommend anything in the 30 caliber range (except the 30-30) due to the recoil. The fastest way to turn off a new hunter is to pound them with recoil.

Set up with low to medium recoil, and an accurate combination and they'll be hooked for life and can upgrade later.