Here's the list of candidates...
Steve Owen ('34 & '38)
Ray Flaherty ('37 & '42)
Greasy Neale ('48 & '49)
Buddy Parker ('52 & '53)
Tom Landry ('71 & '77)
Don Shula ('72 & '73)
Tom Flores ('80 & '83)
Bill Parcells ('86 & '90)
George Seifert ('89 & '94)
Jimmy Johnson ('92 & '93)
Mike Shanahan ('97 & '98)
Tom Coughlin ('07 & '11)
Quite a list to make a top-5 out of. Won't be easy.