Personally i would go for the FI rating. Doing the line training does not guaranty you a job even if you get 500 hrs out of it. There are far more experienced pilots out there having a tough time getting a job. Doing a TR with no job prospects at the end of it is a huge waste money. Instructing/accumulating hrs until the industry picks itself up is a far safer approach in the current environment, at least in my opinion.