I dont think Ghost will be cheap, I'd much rather go for Leddy
Either or is good with me.
Gostisbehere will cost more to acquire, but I think he will help the team more than Leddy would. Not only is he younger, cheaper, and has longer term, but his offensive game will help the team more. Even if the Habs don't succeed in bringing in a forward to help with the scoring, I believe adding Ghost would help in that department, despite him being a defenseman.
I wouldn't stop there, of course. I'd still look for a scoring forward.