In order, and not really even debatable. ACC, Big East, Big12, BigTen, SEC/Pac12
Top four for each conference (post conference tourneys):
ACC: 5, 6, 7, 14 Avg: 8.0 Conf Avg: 59.60 Worst: 219
Big East: 1, 15, 26, 37 Avg: 19.75 Conf Avg: 72.30 Worst: 236
Big 12: 3, 11, 21, 24 Avg: 14.75 Conf Avg: 67.40 Worst: 171
Big Ten: 19, 20, 25, 34: Avg: 24.5 Conf Avg: 66.43 Worst: 172
SEC: 4, 10, 28, 38 Avg: 20.0 Conf Avg: 86.78 Worst: 255
PAC12: 2, 9, 16, 41 Avg: 17.0 Conf Avg: 98.42 Worst: 281
So looking at the entire season, the top teams in order are
ACC, Big12, PAC12, Big East, SEC, Big Ten
Total conference is
ACC, Big Ten, Big12, Big East, SEC, PAC12
Goes to show that the Big 12 and Big Ten do not have the very low bottoms of the other leagues but the Big 12 better top teams would put it above the Big Ten when looking at the conference as a whole. Big Ten top teams are mediocre at best but their worst teams are only below mediocre not scraping bottom of barrel bad as in other leagues.