Your question is not well defined. What are the ranges of the other 8 players? If you do an equity calculation assuming any two cards for all other players, AA has about 34.5% equity vs about 13.7% for 66. If you set two of the villains to AKs and AQs, With ATC for all others the equity for AA drops to a bit under 26%. 66 is still right around 14%. If I give the villains AK, AQ, KK, QQ, JJ, TT, 99 and 88, the AA equity drops to about 14%, but the equity for 66 drops to about 13%. This is closer but still higher for AA. I can’t mathematically prove it, but I suspect AA probably has higher equity for any villain ranges.
I used the link below; you’re welcomed to try some options yourself.
https://openpokertools.com/range-equity.html