Well, that Duke run was great. Four in a row.
So, who's your last 1-seed? People (including me) seem to think Gonzaga, Kansas, and Villanova are locks. But for the last spot, you have:
-UNC. Won the toughest conference in at least 5 years.
-Duke. A ton of top 50 wins. Won the ACC conference tournament. 2-1 vs UNC.
-Oregon/Arizona winner. Not as many top wins as UNC/Duke, but fewer losses too. Only one bad loss between them.
-Kentucky?