Hriston
Dungeon Master of Middle-earth (He/him)
The ranger is more like Aquaman. He can work alone in the sea because he's OUTRAGEOUSLY OVERPOWERED in the water.
On land, he can still punch a foe through a wall and stick tridents in places where tridents don't go.
At the risk of derailing the thread into a discussion of DC superheroes, I see Aquaman as more of a Circle of the Land (Sea) Druid, since he is more interested in protecting the sea and it's creatures from the world of men, than he is in protecting the overworlders from sea monsters, as I would imagine a Ranger of the sea doing. He is surrounded by the animals of the sea and is the leader of a society of sea-dwelling folk, analogous to the society of druids that protects the forest.
Green Lantern is an Evocationist Wizard.
Wonder Woman is a War Cleric of Aphrodite/Hera, whose high Wisdom and skill with Insight allows her wield the Lasso of Truth.
Superman is, of course, the group's Paladin, Oath of Devotion. (His divine smite comes from his eyes?)
Some might want to cast Green Arrow as the group's Ranger because of the archery connection, but I dislike this characterization of the Ranger as specializing in particular weapon combinations. It's pretty clear that in 5E, the Fighter is presented as the weapon specialist and can be expected to outshine any other class in the use of any particular weapon or fighting style, ranged weapons and two-weapon fighting included. I think that's another one that should be crossed off the list of what makes the Ranger unique.
In the wild, the ranger is straight overpowered when prepared. He can work alone there if he feels and he can meet the threat. In the city or a dungeon, he can bring those skills to help the group and be a scout, backup healer, watchman, offensive warrior, and backup defensive warrior.
This brings me back to Batman. Some might want to associate him with the Rogue class, but I think this just clarifies what the Ranger's identity crisis is all about. Batman isn't a Rogue, but sometimes he looks like one. He uses many of the same tactics, goes undercover as a criminal, and even finds himself on the wrong side of the law. I'd be tempted to say he was a Way of the Shadow Monk, due to his eschewing of weapons, except that he is most certainly armored. Of course you could say he was Oath of Vengeance, maybe a multi-class.
But I think Ranger best sums up what Batman is all about. Favored Enemy: Criminals, you learn Thieves Cant. Favored Terrain: Gotham City. He excels at reconnaissance and stealth, but is armored and fully martial, resolving conflict with direct action rather than subterfuge.
Another feature that Batman shares with Aragorn, which I think is telling, if not fundamental to the Ranger, is the secret identity. In a more general way this speaks of the Ranger's identity as a wanderer. No one truly knows him because he's not from around here. He's not really from any particular place because his home is in the wilderness. He inhabits the liminal zone, beyond the bounds of kenning. "Who was that masked man?" the townspeople ask, but it's too late. He has vanished once again into the murky haze from whence he came.