I think the Big 12 is a good conference, but it's a little top heavy. Kansas, Baylor, Iowa State, and Oklahoma are solid teams. West Virginia is defent too. Texas is okay, but after that is drops off quite a bit.
Duke, UNC, Notre Dame, Louisville, and Virginia are all solid teams with Louisville being the weakest and struggling now. I think it's a toss up as to which conference is the best. Let's wait and see how the tournament goes before we make all these claims.
The Big 12 has 6 teams in KenPoms top 25.