There is no "better". It's just opinion. Prelims are as accurate as 1) The vet doing them (positioning) and 2) The people reading them (it is a subjective reading). Experts read the tests, but they are not infallible.
I have working service dogs, I know how important joints are. But, as others mentioned, guarantees are really more of a "good faith" deal than anything. It's a living creature. Nobody can promise the joints will be sound at 2 years (OFA) or 12 months (A stamp). There are many more factors involved than just breeding.
My personal feeling is that you just cross your fingers and hope.
Jackie and the Marcato Shepherds
(and one cat)
Strauss: Service dog/old man
Wesson: The soon to be champion
Mahler: The sporty sable
Loch: Service dog in training
Barrett: The Frikken Tikken