Carr isn't exactly old for a qb. He's in his prime years. He's more mobile, has had more production and is overall a better QB than AD. I really think he'd be a top 10 qb with the Saints. Of course I could be wrong, but I feel good about what I've seen from him over the years.
He's the safest bet out there. Aaron or LJ will require picks, and Rogers will not dedicate himself to the team at this age. This is why he may get a record contract.