Heart says best in the league, but head says somewhere in the top 5-10. We have a hell of a front 7 but the backfield still has some question marks. With that in mind, there are a lot of good D's out there at the moment so I think it's likely we see the Rams up there, but not quite 'there' this season.
Also, being a Rams fan has taught me that I'm only setting myself up for us to fail if I predict us to be best in the league at anything, so 'good but not quite the best' is what I'd have to go with.