A good QB is critical to long term success and it's the most important position. It's not far to compare QB and O-Line in the way that you guys are doing, because it takes 5 players to make a good offensive line.
Other than that, it's hard to say because how you build your team depends on the value you find in the draft... QB may be most important, but I'm not passing on Jim Brown for
John Brodie.
Btw, if you're interested in figuring it out for yourself, then try out
Front Office Football 2004.