Under 2:04 4 times -- no one else has done it more than twice (even including Kipchoge's "sub-2" race)
Under 2:03:30 twice. No one else has done that either
Under 2:05 every one of the past 8 years
Former WR holder, and he beat Kipchoge in that race
9 marathon wins, including 5 majors, and 8 in a row at one point
Has broken course records at 5 marathons, including 3 majors
I have him as 1b to Kipchoge's 1a. Kipchoge is unbelievable. But it's close. If Kipsang breaks the WR (and wins the race), he will add 1 to every number on the list, not to mention knock out the champ.
And don't give me crap about Wanjiru (who only beat Jaouad Gharib by 44 seconds in the "best race of all time" and never even broke 2:05) or Bekele (who has only won one major and only broken 2:05 once).