The answer to this BEST question is really one of location:
I have hunted 3 geographical US locations. Nevada: shots 100-300+ yds. Need a flat shooter, 25.06/270/280/3006/7mm.mag/
S. Louisiana: most shots under 30yd. in heavy brush, deer small, Buckshot works great.
Midwest: Kansas, most shots 75-150yd. .308 is perfect, but anything that will kill clean works. I have used 3006/7.5x55/762.x39 (using US SP ammo) 3030/8mm/ect.
I favor the .30 cal's with 150+ gr. bullits because I think they kill clean and knock down these big deer. Don't have to be moa or traveling at the speed of light, just a big bullit to turn out the lights. The biggest problem is getting one in your sights, that is finding a place to hunt and then having patience waiting for one to walk by, not get buck fever. Our ancestors pretty much wiped out the US deer pop with black powder. The truth is that most of us here, myself most of all, are gadget holics. We need another gun like we need a dose of VD.
P.S. I just ordered another gun last night, go figure.