I would strongly disagree with him not being the #1 DT in the league. In my mind, he is far and away the best DT... not even close.
I would put his value above that of Sherman as well, because no matter how much the game changes, football is still won and lost in the trenches. Look at all the early injuries in Detroit's secondary last season. A great D-line that pressures the QB can still make a bunch of bums look acceptable, but a stud CB can't cover if the QB has all day to throw. Sooner or later, the QB will find an open man and beat him.
I say Watt is the ONLY defensive player right now better than Suh. And that's why so many teams are willing to break the bank for the man. Watt never tasted free agency, and won't until his career is on the down. Suh is an elite player in his prime.