Right now my favorite caliber is the 243 especially for deer, its nice and flat shooting and you can do a wide variety of hunting with it.

Back when I was a kid and only had 2 or 3 irons to choose from, "favorite" probably would have been easy. Since I now have a rack that is fairly well spaced out from small to large it is a case of "favorite according to task"....

Little cartridges for little jobs.
Bigger cartridges for bigger jobs.

Any one of them is the "favorite" according to the task at hand:
.20 air rifle for backyard-in-town plinking
22LR for out of town plinking
223 for prairie dogs (close)
6MM for prairie dogs (far),
270 for coyotes/antelope
308 for bench targets
338 for deer
375 for elk,
416 for something new

It all depends on what the quarry/task is when I'm heading out for fun or for a hunt, but that is just me.

Good Luck and Good Hunting,
EKM

I like my .22-250 chambered in Win M70 VHB. My favorite hunting rifle is my M70 Featherweight .308. Also a .444 marlin in a 1895 outfitter lever gun.

NBH

.375 H&H Magnum. Plenty accurate, very flexible, adequate for all game from Prudhoe Bay to Tierra del Fuego, plus most stuff from Capetown to Cairo. Plus, on edible game from wascally wabbits to deer size, you can "eat right up to the bullet hole", as Elmer used to say.

Mine is my .220 swift, it gets there in a hurry and is fun to shoot oh its a ruger m77mkIIvt . I also like my nef .243 bull barrel, and my h&r 45/70 buffalo classic. And my browing a-bolt .270wsm, savage 116fss .300 win mag. dam i like them all