I am definitely a believer that non-magnums are very sufficient at real life ranges. Also, Europeans have been using smaller calibers for a long time- 6.5 Swedes have killed o so many mooses. However, I tend to think our grandfather's had it right minus new bullet construction. The 25-30 caliber range is really good, and the 30-06 loaded moderately can get down to 16lbs of recoil. So the .270-7mm-30-06/308 are very ideal calibers for a one rifle hunter- which should be the goal for most.
Given new bullet construction, I think you can drop that a caliber. The 7mm will do what the 30 did. Thus, I tend to think that .25/6.5-30 cal is still a sweet spot. If I chose a rifle today it would be a .280ai.
HOWEVER, I was just hunting with one of the best western hunters I've ever heard of, and he is 100% a .243 guy. He also shot his 355 bull 4 times this year for it to expire, and he is a good shot.
My hunting partner this year shot his bull at 387 with his creedmore- about 140gr elds- and he spined it. The bullet didn't clear the spine, and there was no exit wound. The bullet retained about 60% of it's weight. He's also a very good shot- has taken coues deer @ 500+.
I have also shot whitetails with premium bullets in .243 and just not gotten exit wounds if the shot wasn't pure broadside. I just don't trust sub .25, under 120gr bullets to handle whatever shot angle I put them up to.
Thus, I'm a moderate. I want the largest caliber that truly has no effect on my accuracy- minus denial. for me that's about 17lbs if I shoot a lot in a 7.5lb gun with a good recoil pad. So I still hunt a 30-06 shooting 150-165's at 2800ish speeds. That puts recoil right around 19 with the 165's and right at 16.5 with the 150's. I'd be glad to move down to 7mm if it cost nothing, in order to get the higher SD (.280ai or 7mm-08). Even the 270 has enough energy to kill an elk handily @ 750 yards. A moderate load in 270 is very shootable for teenage kids, and the bullet and powder cost is not really different. So I'm not interested in seeing how small I can go. 6.5 is a temptation, but not smaller than that for me.