Gonzaga has by far the best probability of remaining undefeated the longest. In fact, Gonzaga has a 48% probability of remaining undefeated through conference play. That is astounding. What a weak schedule. Gonzaga does not fall below a 50% probability of being undefeated until February 16th. Virginia is the next most likely but they fall below 50% on January 9th. Texas Tech is 3rd falling below 50% on December 28th. Kansas will fall below 50% on December 22nd in the game against Arizona St.
As for remaining undefeated through conference play, Gonzaga leads the way as mentioned. Here are the rest.
Gonzaga -- 48.3%
Buffalo -- 8.6%
Nevada -- 2.1%
Texas Tech -- 1.2%
The rest are all well below 1/10th of 1%. These probabilities will obviously change as the teams get fully connected.