I use both StackOverflow and Quora every single day. I think StackOverflow's approach of staying on topic and building a community around a topic is great for

I use both StackOverflow and Quora every single day. I think StackOverflow's approach of staying on topic and building a community around a topic is great for bootstrapping. But in the long run I think the Quora approach is better. I like seeing startup topics and then serendipitously seeing topics about motorcycles. I don't think I'll ever see a StackExchange topic on motorcycles.