I think Tomlin may be a better coach than Noll. It's a different era now. Noll didn't have to deal with FA, changing players, coaches, etc. Noll didn't have to worry about the salary cap. He didn't have to deal with the media or twitter. We didn't know every last decision he made wrong like we know about everyone today. Noll didn't have to manage players who have $100M contracts.
Noll's Steelers had other advantages, like the draft because everything was secret. Nowadays everyone has the same info on the college kids. We can't hide a John Stallworth from the rest of the teams any more. There wasn't drug testing back in the day. Noll got the best players and the rules helped him. Football is a round the year sport now and the competition is fair and talent exists everywhere.
Noll has rings. But I don't think he's ever come close to facing the challenges Tomlin faces and overcomes yearly. I see a lot of Noll in Tomlin. But the game has changed so much, it's nearly impossible to compare them.
I think it's easier to compare Noll to Cowher or Cowher to Tomlin, but Noll and Tomlin coached in completely different leagues.
Sometimes I actually think Cowher was better than both of them. He just never had a QB until the end. I've wondered would Cowher have gotten more than 4 SuperBowls with Terry? Maybe, maybe not. I do think there's a lot of luck and timing involved with success. We usually give too much credit to winners and not enough to losers. That's never changed and probably never will.