I say it depends on the owner you're facing. If you feel good about your matchups otherwise, go with the safe Defense. If that's the case, your answer is Tennessee.
However, if you need the points go with the Saints. A blitz-happy coach and a rookie QB should give you a few turnovers. Even if they give up the yards, you know there's bound to be a few turnovers and maybe a pick 6. New Orleans may bust on you, but you're going with the hig risk/high reward situation.
Also, with Bell, Thomas and Bush, New Orleans can control the clock if they need to. Seattle can't do that as well.