Well it really depends on who you are targeting. Twitter and Facebook users can be different. I personally am not a big fan of twitter. But there are people who are avid twitter users. Ask yourself, are they are your market?
Facebook as a social network is more effective than Twitter. It gives you more lee-way compared to twitter.
Facebook is much better for the personal use or for business you can generate massive traffic on your blog, Protocols of Facebook are much stricter than Twitter but you can find quality on Twitter for your business promotion.
Ok what i think... If you are on facebook? you can make" double your marketing" by joining twitter. Same things applies if you are twitter only, join facebook to " make double marketing " honestly, both facebook and twitter have same priority for social marketing. hard to compare..
Well Samuel. Most of the replies mention that they are equally important. And I agree to that. These two networks are not replicas and you just cannot ignore one of them. Each one has its own way of communicating with fans and it unique form of delivering your message. My best advise is to be the best that you can on both networks and let your customers decide.