Nimitz and McArthur both submitted plans for the defeat of Japan.
Truman chose McArthur’s and it worked very very well, especially the great idea of not capturing every island.
I am sure Nimitz’s plan would have also worked but that doesn’t take away from McArthur’s actual success.
I certainly wouldn’t say Nimitz didn’t make mistakes, that is certain.
Between the two, I am biased towards Nimitz due to his personal qualities and the way that he led men.
You look at leaders like Patton, Lemay and Halsey, and they were men who knew how to fight both with their brains and with their leadership. Of the three, I think Halsey was the least accomplished at using his intellect towards an end, he seemed to depend more on his aggressiveness and instincts.
The invasion of Okinawa began on April 1, 1945. Truman became President on April 12. There were no additional island invasions between April 12 and when the bombs were dropped on Hiroshima and Nagasaki. The President that went with the island-hopping strategy was FDR.