Tough topic. But if it helps, also consider that from the I-77 and I-40 interchange in Statesville, it is 610 to the Magic Kingdom exit off of I-4.
Depending on how far West you are in NC, that may be another possibility to consider.( FYI - That makes it 610 - 39 = 571 from the I-85 and I-77 interchange in Charlotte).
We've only done the I-75 approach when we got to FL. Coming across from Jacksonville, the last stretch of I-75 to WDW (through Ocala) is fairly flat, and there seems to be more livestock farms than there are on I-95. It was a very nice drive, last time we went that way.
Atlanta traffic can be horrendous, depending on when you drive through.
Hope any of that helps.