Gotta love the "which is best/right" debate...always gets things stirred up.
The real answer is, "it depends".
Depends on what, where, and how you are hunting. And finally, on what makes you happy.
I used a .300WM in Africa on plains game -- size of game ranged from Jackal to Kudu. Worked great, no issues. Most shots under 250 yards, but was glad to have it for the longest shot at 440 yards. Have used other magnums on other hunts, never felt like I had too much gun. Recoil is an issue for some and not for others. Mainly it's a training issue, but if recoil bothers you enough that you won't practice enough with it, it should be addressed. You can put a slip-on recoil pad on for prone and bench (which is the only time I think rifle recoil really bothers most people) and then take it off for seated/kneeling/standing so you get the same ergonomics as when you hunt.
If I had to have one deer/elk gun for everything then it would likely be the .30-06 just cause it does everything in NA, depending on distance and load, and if your ammo gets separated from your gun you can usually find some where you end up. Happily, I don't have to make that choice. For hogs to deer I've been using a 20" barrel Savage .308 just because it's what I like to practice with.
Accurate gun, good load, good bullets, good glass, and mainly, be able to shoot well (holdovers/come ups/reading wind) and any gun will do out to the max optimal range of that setup, for that animal. But I would rather be overgunned than undergunned.
As for the ethics of long-range hunting. Well that's a personal call, but seems to me that a lot of the logic against it does not stand up. I think we can make a universal statement that willingly causing an animal to suffer unnecessarily is a bad thing. But if only shooting when you absolutely "know" the kill will be clean is the rule, then bowhunting would be out, and honestly, rifles would be out over 200 yards for the average hunter. As far as getting closer with a rifle being more sporting, I think that's a personal call as well. A few years back I was on a moose hunt and we hadn't seen one after five days of hard slogging. I was ribbing our Indian guide about it and he said he had shot one right there (as he pointed out the truck onto the road). "From where?" I asked. "From this truck" he responded. I made the half-joking comment that that did not seem very sporting. He gave me a look I'm sure he had practiced on other city boys, and asked me if "I bought my groceries from the store closest to, or farthest from, my house?" For him hunting was a way of putting meat on the table, and unlike me he did not have the luxury of ritualizing the process.
Don't get me wrong, my favorite part of hunting is stalking, reading sign, not knowing if I'll come home with meat or empty handed. And my least favorite part is actually killing the animal. But that's just me. I don't like shooting prairie dogs cause I can't eat them (YMMV) but I don't begrudge the guys who like to shoot em by the barrel load. Just not my thing.
I'm going to try my .338LM out next year, probably on elk, and depending on how the loads work up I'll probably restrict myself to shots over 600 and under 800 yards. Bullet expansion is what will decide the max range. I probably won't have to do the same level of stalk I would to get within 300 yards, but I'll have to do a whole lot more research (on ballistics and load/bullet performance, as well as shooting (I'll put at least 500 rounds of reloaded .338 downrange through this gun before I go after the elk) and I'll keep shooting my .308 at distance on practice ranges and at matches to develop my skills.
So that's the long-range scenario I'm comfortable with. To me it looks like a lot more preparation than the average deer hunt, and I'm pretty sure there's less of chance of a sloppy kill or a lost animal.
I guess if I had to sum up my thoughts on anything from bowhunting to ultra-long distance, it would be: know your limits.
Happy shootin.
