Best Player v. Fit for the System v. Highest Need

In the NFL, each team has a different drafting technique.  They all approach the draft in their own unique way. 

Dallas Cowboys - Best Player Available - The Cowboys tend to draft the best player available at their slot in each round.  They are not bound to making selection based upon need, but more on the quality of the player.  They drafted Dez Bryant, a wide receiver, with Roy Williams and Miles Austin in the fold.  The Cowboys had some other needs in their team, but they went with the potential home run in Bryant and left potential safeties and offensive linemen

Pittsburg Steelers - Fit for their System - The Steelers go after the best player for their system.  They have the zone blitz defense with a larger, active linebackers.  They also look for certain character elements in their draft prospects.  The Steelers tend to spend higher draft picks on offense and build their defense from players designed to succeed in a proven system.

New England Patriots - Highest Need - The Patriots have in their history a background of drafting on a need basis, with picks like Meriweather, Mayo and Mankins.  They filled the needs created by letting players leave via free agency or retiring.  Once a need is identified, they draft the right player to fill the need.  They do have strong depth, but will target a prospect to fill a need.