Brees is the feel good story after being released by the Chargers and going to a franchise that was struggling and still had the post-Katrina feel good vibe. If Brees does throw for 5000 yards then I think he has to get it, regardless of LT breaking a short standing TD record.
No one knew how Brees would react after being released and going to a struggling team as well as coming off major shoulder surgery. As much as I love LT, in my opinion I would pick Brees just because his achievements were not expected by anyone and have exceeded what a lot of other QBs have done in the past decade. In fact, a few " experts " predicted his career was almost over. I think in the grand scheme of things, his season will be a better one than LT's due to a variety of factors.