I had to vote sector 2...but I wanted to stick up for sector 5. Vapor Trails wasn't that great, but S&A and CA are both phenomenal, and IMO they do easily hold up along side the sector 2 output.
As a matter of fact, if you were to trade out Vapor Trails with Test For Echo, I would almost call it a dead heat...but not quite. Test For Echo is just an absolute GEM of an album. I feel bad for Sector 4 because it has my least favorite album (Roll the Bones) and a couple of mid-tier albums (Counterparts and Presto) and then ends on a top 5 all time Rush album (to me at least, I know I'm in the minority on that one).