In the following video, Fool contributor Maxx Chatsko explains whether he thinks Celgene (CELG) or Biogen (BIIB -0.22%) is the better buy. The companies have tracked one another in valuation, separated by as little as half of one percentage point. Additionally, both have promising pipelines that have kept investors' expectations high. Does one stand out? Is it too close to call? Watch the video below to find out. If you are eyeing either company -- or both -- then you may want to use the recent pullbacks as a buying opportunity.