Gotta be the Jets out of those 2.   There was definitely a degree of skepticism about the 49ers, but I also heard plenty of people talking about that game as a potential NFC championship preview, so of course SF is going to come out of winning in Lambeau looking really good in most people's minds.  The consensus about the Jets was that they were going to have to win games 13-10.

That being said, Week 1 reactions suck in general, because they are based on assumptions about who is actually good that are built only on what they did last year and offseason hype.   Green Bay was 15-1 last year, so we assume they're really good this year.  The Bills made a bunch of moves on the defensive side of the ball, so we assume they should have a good defense this year, etc.