Besides earth, what is the next most inhabitable planet or moon in our solar system?
You've actually written the question wrong. *habitable :P
The answer is Europa and Titan.
Europa, an icy moon of Jupiter, is believed to contain more water beneath its surface than the oceans of Earth, which could host squid-like life. However, Titan is the competitor of Europa. It's Saturn's moon. It's temperature is -173 C, allowing methane to exist in liquid form in Titan's oceans. Life is very resilient, and it is a possibility both Titan and Europa support life.