In Western and Northern Canada, my favourite cartridge for moose and bear is the long established .375 H&H. In a slim and proper bolt action (Mag. 98 or derivative) w/22-24" tube, folding leaf sights, receiver mounted peep and QD variable coming in at around 9-10 lbs., I couldn't think of a better rifle a person could own for this purpose. Ammunition is abundant and it is also a easy cartridge to reload for.
Some people argue that the .375 H&H is "overkill" for deer and that a .300 WM or .338 WM are better options. Incidentally I have taken game species with all three cartridges and I can say from experience that the .375 H&H created a larger permanent wound channel without the bloodshot and bruised peripheral effects of the higher velocity cartridges. What more, the H&H is one of the slickest feeding bolts I have ever owned. On a M98 or derivative platform it is absolutely reliable, operates at lower pressures and, if need be, can fire lighter weight projectiles and outclass the .300 and .338 WMs.
However, my rifle is typically zeroed for 275gr or 300gr projectiles. I primarily carry it in grizzly country. In hunting camp, reliability is paramount. Shots are never beyond 300 yards.
It's too bad many people overlook this cartridge on the mistaken belief that it is "too much" gun, yet they consider the various .30 mags and/or .338 mags as being perfect. If a 225 gr .338 bullet traveling at 2800 fps is considered "ideal" by some people for elk, why would a 275 gr. .375 bullet traveling at 2650 fps be "too much"? Illogical and irrational poppycock from people with little understanding or experience, me thinks.
I'm not claiming that it is the best one gun solution for everybody. Far cry. My 7x57mm gets much more ground time for antelope, deer and elk. I've taken moose with my 6.5x55, .30-30 and 7x57mm without incident. Not saying the 375 is necessary, just that it is an excellent cartridge for its purpose and is very versatile.
In a 9-10 lbs rifle w/straight stock and limbsaver, recoil is very manageable, and really no worse than shooting .300 WM. Perceived recoil, I find, is worse in a stoutly loaded .338 WM. In hunting scenarios, its irrelevant.
Many people argue that the .30-06 is a one gun solution to Canada. I agree to some extent. With 180 gr premium you could hunt anything in NA. Load up 200-220 gr and the bears are fair game. However, If you see the merits in running an intermediate 6.5mm or 7mm, the .375 is the perfect marriage for the largest of game species, and will not be "too much" gun for smaller deer if you have two tags.
One of the criticisms of the .375 H&H is that it requires a magnum action, which is slightly heavier. I think within the context of the cartridge and its use this is not a problem. Anybody who has shot any medium bore cartridge in a "lightweight" rifle will know what I am talking about.
There really is no perfect answer when it comes to "which cartridge?". Naturally, this will depend on the individual, their location, hunting style, budget, etc. and they will have to go through a process of elimination to find that ideal. If forced to choose only two cartridges to hunt with for the rest of my life they would be the .275 Rigby/7x57mm and the .375 H&H. And never discount emotional factors. When I am in a chilly fall camp in the heart of grizzly country resting in the wall tent with the wood stove ablaze, nothing gives me a more warm and fuzzy feeling then seeing my pre-64 M70 in 375 H&H perched up against my rucksack.
Any .375 H&H owners/users here? Share you experiences!