Look at some of the 'novel endophyte' varieties - MaxQ, ArkPlus, etc.
Pricey, compared to KY-31, but if you're starting with a 'blank slate', probably worth the extra expense.
I would not, however, recommend killing out a good, established stand of KY-31 to plant 'em. Been there, done that. It was a mistake.
Don't - however - bother with the low/endophyte/endophyte-free varieties. Low seedling vigor, they don't stand up to any sort of grazing pressure, and turn toes-up at the first hint of drought. They may be OK for an irrigated hayfield, but not in a pasture setting in the Southeast, IMO.