Rams. Hands down.
The Raiders had a bad game for sure, but on defense they should be at least average--they were a good defense last year and didn't lose anyone notable, I don't think.
The Rams, however, have a terrible offensive line, a passing offense without any real WRs save for an aging Holt (paging Mr. K9, please go to white courtesy telephone), a QB that is a stiff breeze away from getting hurt, a defense that, well, no, on second thought they don't have a defense.
The Rams will be lucky to win 4 games this year.
JMHO
EDIT: Also, I think the Raiders looked bad last night in part because Denver is going to be better than people (myself included) thought they were going to be. That kid Royal looks like the real deal, and WR was a big question mark for them. As was their OL, which also looked pretty solid.