Biggest Impact Player/Position for 2019?

[*ochocincos*]

There's already been discussion of what some of the needs are for the Bengals going into 2019 based on 2018 performance, but I don't think there's been talk over what position/player would have the biggest impact to the team if addressed.

For me, I think it's close between 3-down LB and right side of OL. I'm even tempted to say RT over RG because I think RT makes a bigger difference than RG. If RT is solidified, it should make for an easier time for RG (although perhaps you could flip it too?). Would a LB make a bigger difference though over OL due to how terrible the middle of the field has (always?) been on defense?

What're everyone's thoughts on which position/player would be the biggest addition come next Spring?