I don't trust either.
Autocheck said my car was 100% fine.
Carfax found a minor car accident that I verified with the previous owner and dealership records. But Carfax has had incorrect information and inaccurate dates for other cars in my house that my Dad was the original owner and kept until the day they ended up in the junkyard.
I judge more by receipts, quality of any repairs and the openness of the previous owner about any work that may have been done more then anything.
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-99' Zenith Blue 5-spd...didn't agree with a center divider on the freeway
-01' S Orient Red Metallic 6-spd...money pit...sold to buy a house