Easily in no particular order:
1. Paul Brown because he won 7 Championships not just 4. And innovated a multitude of things still used in the NFL including the radio helmet. Consider this CLEVELAND once DOMINATED the NFL.
2. George Halas 6 championships but also had to run the whole team in an era when the NFL was struggling to succeed. He maintained a .682 win percentage in 40 years of coaching.
3. Curly Lambeau also 6 Championships a big reason the forward pass works so well in the NFL
4. Vince Lombardi 5 Championship titles and has his name on the trophy for a reason.
5. Guy Chamberlin 4 Titles same as Belichick but he did his in only 6 seasons. He has the greatest win percentage in the NFL with .784. There is a reason the Hall of Fame is in Canton. And in case you are counting he actually had the first 2 undefeated seasons in NFL history.
6. John Madden only won 1 championship but holds a .759 win percentage right behind Chamberlin but with significantly more games.
7. Don Shula has sustained a .677 win percentage in 33 years of coaching has taken 2 separate organizations to the Superbowl and actually completed the perfect season and then followed that up with a back to back superbowl.
8 through 10 are debatable but it is after all my opinion not yours
8. Blanton Collier a short career with only 8 seasons. But he never finished less than 2nd in his Division. NEVER and with the Browns. The last time the Browns won a title was with Collier they havent been relevant since. He had a .691 win percentage.
9. Bill Walsh one of the West Coast Offense pioneers. 6 Division titles and 3 Super Bowls. Perhaps bias, but I prefer Walsh over Belichick.
10. Tom Landry again bias for that era of football (obviously no bias for the Cowboys). 18 playoff seasons. One of the great defensive minds of football. IMO he is the reason too much of America fawns over the Cowboys. Sure Jimmy Johnson won the Superbowl but Landry built that cult and coaches have been clinging on ever since.
Reasonable Arguments Can Also be made for:
Bill Belichick - I certainly wont fault anyone for including Bill in their top 10, he just isnt in mine.
Chuck Noll
George Allen
Jim Lee Howell
Steve Owen
Ray Flaherty
and Greasy Neale
EDIT: Joe Gibbs probably has a place in here somewhere as well.