The Infinity Gauntlet is all the stones on one glove. But the one ring is the ring to rule them all. It's LORD OF THE RINGS--not RING.
"Three Rings for the Elven-kings under the sky,
Seven for the Dwarf-lords in their halls of stone,
Nine for Mortal Men doomed to die,
One for the Dark Lord on his dark throne
In the Land of Mordor where the Shadows lie.
One Ring to rule them all, One Ring to find them,
One Ring to bring them all and in the darkness bind them
In the Land of Mordor where the Shadows lie."
Apologies to Jim Starlin, but Tolkien's is a monumental fiction that encompasses far more than what the Marvel Universe represents. I just don't think there's any comparing them. I also wonder if you can even call Bilbo's ring a MacGuffin, since the MacGuffin isn't supposed to really matter--it's just a plot engine--whereas the rings are fundamental to the story and character development, not simply plot engines.
The Ark in RAIDERS OF THE LOST ARK is more like a true MacGuffin--although it plays a key role at the climax of the movie--because in the end it doesn't matter; Spielberg shows it being completely ignored and relegated to obscurity in the final shot.