Almost equal to me. Both are better wild caught, as many captive strains are ultra inbred. For looks, apples and oranges. JD's are among the most beautiful of blue cichlids, while Oscars do a great job of the orange/red spectrum. JD's are smaller, so better for a 55g. But they also are a little less interactive than O's.
If a guy was running by with an Oscar in one hand and a JD in the other, screaming, "Save my fish! Pick one!", It would take me a moment to decide. I'd probably take the Oscar, but JD's are right up there.