What do you think about hunting with a heavy rifle 30-06 vs a light rifle .223?
Neither a Garand nor an AR in 5.56/.223 would be my choice for a multi-purpose hunting rifle.
But, my official "huntin' rifle" is a scoped bolt-action .30-06 with a 24" barrel and a walnut stock. Weighs about 9 lb., but that does include a decent-sized scope. It's a PITA to drag up and down mountainsides through the brush, and I'm a pretty well-trained fitness freak certified as a strength trainer.
And I've carried a Mini-14 while scouting around in the brush (for targets of opportunity like jackrabbits, coyotes, or whatever, and just because).
Damn, if that Mini-14 wasn't a real
pleasure to carry on steep trails and through thick brush, compared to the .30-06. Except from the accuracy an AR affords, I'd take the Mini over the AR any day, to shoot .223 at moderate ranges; an AR's parts stick out in every %@#$ing direction, and you know what our brush is like when it's dry!
Another little gun I have and like is the Marlin 1894C, a .357 lever gun that shoots .38's very accurately. Good for rabbits with .38's, all the way to big game at closer ranges, with hot loaded .357 carbine loads that can be up there with factory .30-30. 6 lbs., 36" OAL, and man, straight grips carry like nothing else.
For a multi-purpose
hunting rifle, I'm looking now at the Howa Ranchland Security rifle, a short-action 20" bolt gun in a Hogue stock. It's light, compact, and inexpensive, and Howas are accurate, durable guns (think rubber-armored Model 7 for half the price, and unlike the Remington, it has a bolt-locking 3-position safety that you really need in our brush). Maybe 7mm-08, or maybe .308.
The AR is a fun, expensive toy. I've used it only a little, but one time I did, it won me some prizes at a charity bullseye shoot. I'd be reluctant to call it a real multi-purpose rifle. Sure, you can get more uppers and shoot .50 Beowulf and 6.8 SPC, but it's not like you couldn't buy a whole rifle for the price of each upper.
That said, for target shooting, plinking, coyote hunting, and just messing around, the AR is a helluva toy, and highly recommended. And .223 is still cheaper than other rounds, provided you're shooting modern ammo -- cheap to reload it, too. Surplus changes the equation, but I wouldn't bank on any given caliber of surplus ammo being plentiful and cheap forever.
All of the above is my own opinion, subject to change without notice, your mileage may vary.