There are a few arguments for Hull over Ovi.
In his NHL prime they played 70 games, not 82. Another 12 games a year and his compiling stats and season individual totals likely look far more impressive.
Hull spent 7 years of his career in the WHA, when he was still playing at an extremely high level. He had scored 50 goals the year before he left the NHL. Obviously the WHA was an inferior league lacking the depth of the NHL but his career statistics likely shine much brighter if he stays in the NHL his entire career. I believe he would have competed for more rockets in his 33-40 year old seasons. People tend to ignore that the NHL also became weaker due to the emergence of the WHL. When Hull came back to the NHL at 41 he still scored at a 18 goal, 52 point pace.
The other argument is regarding his overall hart records as opposed to wins alone. These are their top 3 finishes.
Hull - 1, 1, 2, 2, 3, 3, 3, 3
Ovi - 1, 1, 1, 2, 2
Fair to say Hull was much more consistently a top player in the NHL. Hull was more like Crosby than Ovi in that regard, but obviously a better goal scorer by far.