Campaigns have increasingly resorted to Facebook because it has the highest number of users among social media platforms. The question as to whether Facebook is a more favorable choice of social media than a blog for political purposes must be addressed. In this comparative study, cross-sectional data collected in the 2009 and 2014 Taiwan local elections were used for exploring the differences among voter motivations, perceived credibility, and dependency between the use of political blogs and Facebook. In addition, the impact factors regarding the relationship between blogs and Facebook dependency were analyzed. The findings indicate that voter motivations, perceived credibility, and dependency were higher for political blogs than they were for Facebook, suggesting that in a political context, people prefer blogs to Facebook. The results of regression analyses indicate that the motivation for debating political topics was a significant predictor of the dependency on blogs, whereas motivations for general information and entertainment were related to Facebook use. The perceived credibility was not related to blog use; however, accuracy and information depth were significant factors for the use of Facebook. The reasons for the differences between peoples’ use of political blogs and Facebook are discussed in this paper. This study advances our understanding on the variations in people’s use of different social media platforms in a political context, and few studies have investigated this topic from a user-oriented perspective.