Orra 14

Orra 14 was a lush Earth-sized forest planet in the Orra system. The planet was almost entirely covered in forests and swamplands, with shallow, marshy freshwater seas covering much of the planet's Northern hemisphere. The planet had an atmosphere of about 75% Nitrogen, 23% Oxygen, and 2% Argon, making it one of the closest atmospheric analogs to Earth in the Omniverse. 
The Combined Andromedan Republics settled Orra's Southern Hemisphere, constructing massive environmentally-friendly housing complexes in the canopies of the forests. The largest of these such cities was Karavorth, with a staggering population of 7 billion at its densest. The planet as a whole was able to comfortably sustain 100 billion human-like beings at once.