A question with no "right" answer.
Individual tastes differ.
Individual animals within the same species differ. I offer my experience with 20+ moose and about 75 caribou.
What it has been eating, what it has been doing, perhaps (bear on the salmon streams vs blueberry slopes.... Animals stressed from running vs those killed unaware, etc.)
Chalk in how it is killed, temperatures, how it is taken care of, processed, and cooked.
Not all of us (few in fact) have sampled all the game meat availble. So all opinions are valid.
In my own case, from a very general perspective, I rank it wild sheep, musk ox, caribou, moose, then deer and pronghorn, elk, bear.
The very best caribou I have eaten will outrank all the others I mentioned on the individual meal taste test
Some personal opinion/comments that may or may not be pertinent:
If you have had bad caribou, it was probably a bull in rut, or not properly taken care of.
I don't believe I have ever seen any "marbeled" moose meat from the 20 something I have eaten.
Musk ox is marbeled, and not that different from beef, (the several roasts I have eaten, killed by a friend, were excellent). If you had bad musk oxen, see above caribou sentence. Limited sample to be sure, but from 3 different animals. And not really choice cuts. (We aren't that good of friends it appears...:) )
Good post with a couple thoughts... in the last four years alone I have had a part in butchering of over 20 bull moose and since i killed my first bull in '65 have had a part in a whole bunch of them. I have never seen even the first indication of marbling and have seen some ridiculously fat moose.
I agree totally on carbon at its best being as good as it comes, even from late winter animals.
The biggest problem with musk oxen is the fact if freezes almost immediately after expiring. It is hard to slow that down. Frozen solid it does not ever age properly and is incredibly chewy. Had some from a summer cow and it was awesome.
Since you mentioned sheep... I think they get a lot of credit for the mystique of being sheep. In virtually all blind tests I have done with sheep they seldom make the top two and carbon is often the meat picked when folks are certain they are eating sheep.
