No doubt Belichik is #1. He's likely going to be in the running for one of the top coaches of all time, although I think that depends on how he fares after Brady hangs up his cleats.
I think that Coughlin is too high, but I understand the weight of two rings. However, I would argue that while he does his best when his back is against the wall, the converse is also true that he fails to deliver on high expectations. He's a bit of a one trick pony playing the us-against-the-world card, albeit very well.
I have no issues with Sean Payton's ranking. He's a great coach except for the Bountygate asterisk.
Which brings us to McCarthy, who seems to keep a level ship despite lofty SB expectations each season. Not many coaches went 15-1 after a SB win. They ranked Tomlin a spot higher, offering the excuse that 8-8 was due to injuries. How about finishing 10-6 and winning the SB when your team has the most injuries in the league? That should carry some weight.
I think that Harbaugh is ranked way to high. I wouldn't put him above any of the other coaches in the top six...yet. His one SB ring puts him no higher than any of those coaches. He did benefit from inheriting a great defense. Which gets to my real issue: It's tough to rank coaches (much like players themselves) without considering those around them. They could rank the GMs at the same time and then use that to weight the coaches rankings. A coach that consistently delivers despite poor personnel moves should be ranked higher than an average coach that has a superb GM keeping the talent pool rich. It's no easy analysis though.
My ranking would go:
1. Belicheat (I like that name)
2. Sean Pay-to-hitton (okay, that sucks but I tried)
3. Tom Coughlin
4/5. Tomlin/McCarthy - two equal coaches with equally good GMs and team management
6. John Harbaugh
My only comment from the rest of the list is that John Fox should be ranked higher. He's done much with little. IMO he would have done equal or better than Coughlin with the NYG.