I much prefer to work on the defensive backs if the Steelers want to spend any money on defense. A decent coverage guy to not leave the opposing team's #1 receiver open every time would be nice.
I want the offensive line repaired. I want to see Roethlisberger get 5 comfortable seconds in the pocket on almost every down like Eli and Brady, and many other QBs in the league get. And it's not just about fixing the run because the Patriots and Giants have zero rush and yet the line still keep the quarterback well protected.