Bill Polian is by far the best front office official, regardless of position (general manager, president, director of pro personnel, etc.). Why? Because, he understands the draft.
He got his quarterback in their first draft in Peyton Manning. Then, he found ways to make his quarterback find success; adding weapons like Edgerrin James and Reggie Wayne. He also used high picks on pass rushers like Dwight Freeney.
Once Polian got his basic pieces in place, he was able to follow the fifth and final rule of the draft.
Need should typically be a large proponent in deciding who you draft. If you're getting atrocious safety play, you'll likely want to add a new safety via the draft or free agency.
However, if a player who's rated even higher on your board is left for your picking at a position not of need, you take him in order to get the best players possible.
With Reggie Wayne and Marvin Harrison, the Colts didn't come into the 2007 NFL Draft thinking about a wide receiver as a top need. However, when Ohio State receiver Anthony Gonzalez was available for the picking, they snatched him up.
They did the same in 2009, by drafting Donald Brown out of UConn despite having Joseph Addai.