This all depends on how you define best. XU has had the most consist success in the last 20 years. OSU has had the highest peaks of success in the last 20 years. UC has the most national championships and is historically probably the best but hasn't done anything noteworthy in the post season since the 90s.
Dayton is a distant 4th despite beating Ohio State 2 times or whatever it is. Seems like a weird way to define success when things like conference regular season champs, conference tournament champs, sweet 16s, Elite 8s, Final Fours and national championships/appearances are all available to use as resume boosters. In all those aspects, Dayton pales in comparison to the other 3.