My vote would be for the Mauser 98. The Canadian Ross was very accurate, but I wouldn't recommend shooting one.
I'm not sure how the Lee Enfield got a rep for good accuracy. It had serious bedding problems, which were neverly completely solved, and the rear locking lugs result in a lot of harmonics.
After WW1, it was said that the Mauser 98 was the best hunting rifle, the 1903 Springfield was the best target rifle, and the Lee Enfield was the best battle rifle. I believe the above assesment is accurate, but I believe the 98 had the highest potential accuracy, but that the Springfield's sights were better suited to target shooting.
I know that between the World Wars, the US tested the 1903 Springfield, 1917 Enfield, and .30-06 Mosin Nagants for accuracy. Of the three, the Springfield came in first, the Enfield second, and the M-N last. However, the Enfield and M-N may have been hampered by oversize bores.