IMO, Twitter is getting more traffic and popularity because of the trends in mobile social networking connectivity but Facebook dominates in general both in social media features and traffic popularity and use.
I still say people will click on anything at twitter. Even if they are those shorten tiny urls that you have no idea where you will end up. They still click them. I don't think a lot of the traffic is very good though. Very high bounce rate, but you never know. Twitter is difficult to say much with the character limitation. For quick advertising twitter is fast and easy. Facebook requires more work and maintenance I think.
Until a short while ago I would have sided with Facebook. While you must be active with both to make them good for business usage, Facebook requires much more maintenance and is so heavily saturated that effective marketing becomes more difficult. Twitter on the other hand is much less time consuming and it is simple to build a large network rapidly.
Both are best. I preferred facebook. it is easy, nice and very user friendly platform provided by them.
Facebook is better moreover it can integrate with twitter so you don't need to look on twitter all the time for posting. Only post on fb.
Facebook and twitter are entirely different. FB is like god where as twitter is like an assistant working with FB.
These social networks keep changing from time to time. People go after something innovative. Now its facebook era, later it would be something else, and so on. These social networking sites need to compete in this race for survival. Maybe this is one reason Google could not do much in the social networking arena.
Facebook is better than twitter bcoz facebook have no character length where as in twitter you can enter limited text or character.