Kepler-22b

Located 620 lightyears away from Earth, Kepler 22b is probably the likeliest candidate for a habitable exoplanet. It is located in the habitable zone of its Sun, the only "Super Earth" discovered to have this characteristic as of yet. This gives it the rather nice quality that its average surface temperature, of 74F is similar to that of Hawai'i (hotter than Earth's average temperature). Terraforming it would therefore be easy, perhaps even unnecessary. All it would consist of is ensuring a proper atmosphere as well as the presence of water. If Kepler 22b is already inhabited, ethical issues would stir up, so it would be better to leave it unchanged and coexist with whatever life it may have.