Having said my piece about the B-25, I will now say that my choice for "best ship buster" would have to go to the Avenger, with one reservation. Being an aircraft that could land or take off of carriers (as the norm) gave the Avenger an inherent advantage over land based aircraft, because it made it less problematic to get the "ship buster" close enough to the ships that needed "busting." The Avenger could also carry either bombs, rockets, or torpedoes, which gave it flexibility not enjoyed by some of the other aircraft mentioned. It's drawback was that the Avenger didn't carry much in the way of guns, which leads us to my one reservation: The F6F Hellcat. I have never seen or heard of a Hellcat actually carrying a torpedo, but most of the specifications for the F6F list that ability. It could certainly carry an adequate bomb or rocket load, had 6 .50 caliber machine guns for strafing, and once shed of its external ordnance, could take care of itself with any interceptors.
I have heard that in the latter stages of World War II, many carriers were taking more Hellcats to sea in place of Helldivers and Avengers, since the Hellcat was more versatile and just a competent of a bomber as the Avenger or Hellcat, with the added expertise in knocking down kamikazes.