Top to bottom the Big XII IMO. Every single Big XII program takes their basketball program seriously, including TCU who most figured would be the league doormat when they were added for football reasons, there simply are no pushovers and KU is a way more consistent top dog than programs like UConn, Syracuse, Villanova and UL.
The Big East IMO resembled a CBB version of the Barclays Premier League. For the BE you had a big collection of programs that each all had some type of historical significance save for USF, along with a lot of easy drives for road games. It made for great TV, but end of the day the bottom 4-7 teams were usually layups especially at home, where the Big XII the last place team is typically dangerous especially on the road.