For small or young hunters, .243 is a great caliber. Not much recoil while shooting while still having enough punch to take down a deer hit in the vitals. Great caliber for fields and open woods, however being a small size round it deflects off brush easily.
My next suggestion would be any .30 caliber such as the 30-30 or
30-06. To my knowledge more whitetails have fallen to these calibers than any other caliber. .30 caliber is a bit more effective than .243 for brush or thicket hunting. My favorite is a Marlin 35 rem. I have hunted from the Canadian border to Texas with my 35 and I saw no issues. The 35 rem has a nickname here in Vermont of the "pumpkin chucker". It is a massive piece of lead to smash through brush. It is devastating to deer often taking them off their feet when hit. I can still shoot out to 200 yards after some practice. Though, I have never shot a deer further than 90 yards away.

Whitetail Strategies Guide Service
Fred Scott Owner/Head Guide
www.whitetailstrategies.net