BPA within reason.
And BPA is based on your system and standards, not anyone elses.
QB seems to be the exception even for the most stirct BPA drafters.
If you have no QB and your turn comes up anf your board has 2-3 players slightly ahead of a QB that you expect to be a star anyway, you take him.
That applies to the other positions too, but much less so.
Bottomline is if you fill your roster with the very best players--ones you feel can play a long time in the NFL--you will come out ahead of some team force feeding lesser players into slots to fill needs. Players get hurt or become free agents. Pittsburgh, for example, drafts very forward-looking.
It's best to draft looking forward at least as much as the very near term. That says, take the very best players you can.
Just like said. If the value does not match your needs then try to trade up or down to make them match.