I would go for the SBD, but was the Helldiver responsible for the most Axis shipping sunk in the Pacific?
Or is that wrong information I have in my head?
Edit: I found something from Warbird Alley.
Warbird Alley: Curtiss SB2C Helldiver
History: The Curtiss Helldiver, despite a reputation for being difficult to handle at low speeds, was responsible for the destruction of more Japanese targets than any other aircraft. The Curtiss SB2C single-engine dive-bomber joined the fleet late in 1943, joining the Douglas Dauntless as the primary attack/bombing planes for the US Navy. The two-man Helldiver had a top speed of 295 mph and good range, making it an essential tool in the far reaches of the Pacific war.
With underwing and bomb attachments, the Helldiver could carry 1,000 pounds of bombs or an internal torpedo; later improvements included an up-rated Wright Cyclone engine and rocket hard-points. It carried two fixed forward 20mm cannon and machine guns in the rear cockpit.
Only 26 of the 7,000 Helldivers built found their way to the other services; the plane was so valuable in the Pacific theater that the Navy absorbed nearly every plane. Postwar, the Helldiver found further use with the French, Italian, Greek and Portuguese Navies and the Royal Thai Air Force. Only one airworthy Helldiver remains -- with the Commemorative Air Force in Texas -- but at least one more is under restoration to airworthy status.
===========================================================
I suppose even if it did sink the most, it still might not be the best aircraft.