Quora and YA. I personally think GAG is the best for having fun. Quora is the best for learning and growing as a person, but it is very strict and serious. YA is the worst because the people there are stupid and mean-spirited. A lot of the questions on YA are very frustrating, a thousand times worse than GAG's troll questions.. I have used YA for two years, Quora for two years, and GAG for a couple of months. GAG and Quora are the best, for me at least.