It's a good question, and like most things, the answer depends on your goals. One thing that is pretty universal, is that you should always go after the largest influencers possible. For more niche content, it may be the case the there aren't many big players and thus no major influencer, so a more broad approach of targeting many publishers, might make most sense.
If the content you are creating is of interest to a broad array of content consumers, hitting publishes with large syndication networks often works best. Getting a good understanding of how content is typically syndicated in your particular niche can give you incrementally better results than just guessing at who the biggest tastemaker is. Sometimes it isn't very intuitive, and comments and social sharing indicators of popularity don't necessarily map to the way that content is syndicated across outlets.
Tools like http://www.getlittlebird.com/ can help you identify how content is syndicated within your niche, and can help you identify the most influential writers, editors, and outlets.