Historically, the ACC is a much stronger conference than the SEC, yes. And while most know UNC has been better than Kentucky in the modern era, I think you could even go back to when Dean Smith started (1962 season, I believe), and UNC would still top UK. However, Kentucky dominated the 40's and 50's - and that's what given them a HUGE advantage.
I tend to think the SEC and ACC/Southern were more or less even in the 40's and 50's. And this is significant, because Kentucky gaining their historical advantage during the early years in a quality conference means more (they weren't stockpiling points against a creampuff league). By the 60's, the ACC had certainly surpassed them. Here's a look at how many times teams from the SEC and ACC/Southern had been to the Final Four or nationally ranked between 1939-1959. The SEC has a combined 27 seasons (obviously UK helps a bit, but NCSU and UNC match that #), while the ACC has a combined 24 seasons. FWIW, the polls were only 20 deep back then.
SEC
Kentucky (14)
Vanderbilt (3)
Miss State (3)
LSU (2)
Alabama (2)
Auburn (2)
Tulane (1)
ACC/Southern
NC State (8)
UNC (6)
Duke (4)
Wake (3)
Maryland (2)
West Virginia (1)
Between 1939-1950, the tournament only fielded 8 teams. Kentucky was in there four times, while UNC was in there twice. So, only plus two from that. Yet, Kentucky actually won the SEC 10 times during that 12 year span. There weren't enough spots for all of the conference champs (and certainly some schools deferred to the NIT). I believe Kentucky was a legit Final Four/Title contender in 46, 47, and 50. Also, the '54 Kentucky team was undefeated. They declined to play in the postseason in 1954 because three of their starters were ruled ineligible - due to already having graduated (rule has since changed). That team was ranked #1 in the country. That's 4 squads that easily could have racked up way more points for Kentucky - not to mention all of the conference champs that were left out of the tourney.
The AP Poll started in 1949. Of the first 7 years of the AP Poll (1949-1955), Kentucky finished in the top 3 every season - while UNC didn't have a top 10 finish until the 1957 season. I personally don't think it's splitting hairs. Kentucky is ahead of UNC by almost every metric. I think the best argument to make for UNC is they've had more success in the past half-century - and it's certainly more challenging to win championships in the modern era. But, I don't feel like it's necessarily fair to discount titles from the early years if we really want this to be a true representation of all years. I don't give title teams from the 40's credit for Round of 32 and Sweet 16 wins, however - because they obviously didn't have to play those games.
