WOW for a minute there I thought I was reading one of the .223 for deer threads...
This said, from my perspective, if the hunter is capable with the firearm, and uses a proper weight for caliber and of decent construction for the job, there are a LOT of calibers capable of take a moose cleanly. I believe that what a person shoots "best", is better than what someone else thinks they should use.
I see a LOT of folks at the ranges with rifles that are simply WAY too much for their abilities to shoot properly. Even at 100yards they flinch, and pull shots off to one side or the other, all the while jerking the trigger anticipating the recoil. All this, and most aren't even shooting magnum calibers, just what the friend, or fellow at the gun shop, or the latest magazine said was "the best thing going". For some a .270 is more than they should be shooting but this doesn't mean they aren't capable shots, or that they shouldn't be hunting, simply they either need to shoot more, or get something with a bit less oomph, that they can shoot more accurately.
I have, and shoot a number of calibers, one being a 25-06AI, I had the standard version but gave it to my daughter. Of them all that particular rifle was simply a walking death stick for anything I chose to put it to task on. The main reasons are it is accurate, has little recoil, and plenty of energy with most weight bullets to get the job done. With most of the 115 through 120gr bullets, it has plenty of power to easily disrupt the internal workings of even the biggest critters roaming around the woods and prairies of N. America.
Yes there are bigger calibers, and they drive bigger bullets, and make bigger holes in stuff. And if I were hunting something that might hunt back I would be inclined to look into them pretty hard.
Bottom line is being comfortable shooting what ever caliber you choose, being accurate with it, and confident enough to put it where it needs to go when the time arises. It does neither the person behind the trigger nor the game in the scope, any better to shoot a large caliber heavy bullet into a non vital area, and it won't kill things any quicker than a properly placed shot through the vitals from something a bit smaller and possibly faster. The key is and always will be putting the shot where it needs to go.