No way B12 or ACC are top basketball conference without UConn as a member!
There is a difference between being the best conference which arguably is the ACC on a year in year out basis and having the best team in any given year. It isn’t a perfect measure but if you look a Final Fours, the ACC seems to have teams almost every year. And it isn’t just 1 team. UNC, Duke, Virginia, Miami, Syracuse and NC State have all made the final four. The last 10 tournaments,2014-2024 no 2020, ACC teams have made the Final Four 7 times. They have had 2 teams make it twice, and 6 different teams got there. 3 different teams have won the title. That suggests a league that is deep in quality on regular basis.
In any given year a conference can be up or down, but I think NCAA tournament final four runs by multiple teams indicates that the league is deeper than others.
Being the best league does not mean you have the best team. Over that same period UConn it could be argued was the best team. Even if it was playing in lesser conferences. Nobody would argue that the AAC > ACC. Even the biggest NEWBE fans would be hard pressed to argue that it is superior to the ACC, though no doubt some would try. I am not sold on the Big 12. It is also a bit tricky to evaluate them. Oklahoma made the Final Four from the B12 but isn’t there any more. Houston made it from the AAC but is now in the B12. But I don’t think it is as good as the ACC. In any given year, sure, but over time, the ACC is still #1.