In general Aang finesse over the elements is notably better then Aether. Aether biggest advantage is his body. He's crazy strong, bulky, and fast. Most final foes in each of the nation is a demigod (or minor gods) or something equivalent, with the water nation final boss being a planet eating whale. Aether typically gets help for final boss fights, so its hard to say how to scale the lad.
The wind nation was a rampaging wind dragon (The god of wind helped fight the dragon) The earth nation was an unsealed water "god" called the lord of the vortex (various demigods hyper powered up the traveler) The electric nation was the lightning god herself (We didn't win per se, just out willed her with the willpower of the traveler and her nation) The plant nation was the electric god homunculus (gone rogue) piloting a deus ex machina (received a massive wisdom buff by the plant goddess) The water nation is a planet eating whale (The water dragon used his power to suppress the whale while we fought it)
