Quora is the only one of these that interests me primarily because most answers are posted by people using their actual names. Yeah it's not perfect and it has a lot of issues, but this is a big selling point for me. There are advantages to anonymity, but there are also advantages to sticking faces onto posts. Quora should be the place for the latter, and should play that up more.
Yup, the login wall is a major PITA. Enforcing that for people who simply want to read the content is a mistake IMO. However, Quora made the decision that it would force enough signups for it to be worth it...not sure I agree, but they have more data available on the issue than I do.
Facebook login required? Forgitaboutit. I've never had a facebook account and never will (sure, I know you maybe can use another service...but just it isn't worth my time).
Quora was started by ex-Facebook CTO / VP Eng, who previously lead "Facebook Platform", i.e. the login requirement now seen at Quora. However, most of the world moved on.
Quora has some really interesting content, but there's also a ton of bullshit. A significant portion of the questions I see on my feed are of the form: "how do I get into <famous school>?", "what was <famous person> like in college?", "how do I get a job at <famous company>?, "what is <class> like at <famous school>?, what is <some very specific fact> about <famous company>'s <famous product>?
All of which are topics that most people, even reasonably intelligent people, are interested in. They may be beneath your tastes, but that does not invalidate them.
